Plants
Ferns
A fern is any one of a group of
about 12,000 species of plants belonging to the botanical group known
as Pteridophyta.[3] Unlike mosses, they have xylem and phloem (making them vascular plants). They have stems, leaves, and roots like other vascular plants. Ferns
reproduce via spores and have neither seeds nor flowers.
Ferns first appear in the fossil record 360 million years
ago in theCarboniferous but many of
the current families and species did not appear until roughly 145 million years
ago in the early Cretaceous (after flowering plants came to
dominate many environments).
Ferns are not of major economic
importance, but some are grown or gathered for food, as ornamental plants, for remediating contaminated soils,
and have been the subject of research for their ability to remove some chemical pollutants from the air. Some
are significant weeds. They also play a role in mythology, medicine, and art.
Pong Pong
Where seen? The Yellow-eyed pong pong tree is a commonly planted tree
in our parks and roadsides and is also sometimes seen growing wild on our
shores. But the beautiful Pink-eyed pong pong tree is rare and only sometimes
seen on our shores and coastal forests.
Features: Tree up to 15m tall, but in
Singapore usually shorter. Bark fissured, flaky, grey to brown with lenticels.
Leaves (12-30cm long) oval, dark green and glossy, held in dense spirals at the
tips of the twigs. Flowers (about 5cm) white appearing at the tips of the
twigs. Produces a white sap. Fruits (5-7cm) spherical or ovoid, with 1-2 seeds.
First green then pink, rosy purple and finally black. The
fruits float are dispersed by water. When they wash up, often only the fibrous
husk is left, around a hard
stone.
Human uses: According to Burkill, only the
seeds are poisonous and no other part of the plant is toxic. In the
Philippines, the seeds were used as a fish poison in small streams. The wood
produces a fine charcoal that was used for gunpowder by the Thais.
Oilpressed
from the seeds were used in lamps but produces an irritating smoke. Medicinal
uses for the oil include treating itches, rheumatism, the common cold and as
hair oil that doubled up as insect repellent.
According to Corners, the fruits are poisonous and native medicinal uses are
made of the bark, leaves and oil extracted from the seeds. According to
Tomlinson, some native societies use the fruits as a means of committing
suicide. According to Wee, the tree contains cerberin or cerberoside. According
to Giesen, cerberin is similar in structure to digoxin, found in foxglove,
which kills by blocking calcium ion channels in heart muscles and disrupting
the heartbeat. More ominiously, it is also suspected of being used in an
increasing number of murder cases. The bark, sap and leaves are used as a
purgative, and for inducing abortion.
Status and threats: Cerbera odollam is
listed as 'Vulnerable' while Cerbera manghas is listed as 'Critically
Endangered' on the Red List of threatened plants of Singapore.
Interesting Facts
In August 2009,
Lim Poh Bee chanced upon a Tanimbar Corella (Cacatua goffini) chomping
on the green fruits of the pong pong (Cerbera odollam) at Pasir Ris.
Using one foot to cling tightly on to the perch, the bird uses the other foot
to grasp the large, smooth fruit, its sharp claws getting a firm hold on the
fruit. It then uses its strong sharp bill to take a few large bites before
abandoning the fruit.
This introduced
parrot has adapted well to its new environment, having found its food niche in
the urban areas of Singapore. It regularly eats fruits that other animals
avoid. The hard fruits of the
pong
pong is one of them, eaten when still green. Once they ripen, they
become hard and fibrous.
The bird also
takes the long, hard pods of the golden shower (Cassia fistula),
perching on a nearby
branch to chew on the pods or
grasping the pod with both feet to take bites on
it. This is an exotic roadside tree, planted for its attractive bunches of
yellow flowers.
In the case of
the starfruit (Averrhoa carambola), another exotic tree, it walks from
branch to branch grasping one green fruit after another. It then brings the
fruit to its bill where the seeds are extracted. The rest of the fruit is
discarded, giving the impression that it is a wasteful eater. But the bird is a
messy eater.
, commonly
known as the Suicide tree, Pong-pong, and Othalanga, is a species of tree
native to India and other parts of Southern Asia.
It grows preferentially in coastal salt swamps and in marshy
areas. It grows wild along the coast in many parts of Kerala, India and has been grown as a hedge
between home compounds. It yields a potent poison,
often used for suicide or murder [1].
The fruit, when still green, looks like a small mango,
with a green fibrous shell enclosing an ovoid kernel measuring approximately 2
cm × 1.5 cm and consisting of two cross-matching white fleshy halves. On
exposure to air, the white kernel turns violet, then dark grey, and ultimately
brown, or black. The plant as a whole yields a milky, white latex. Cerbera
odollam bears a close resemblance to the Oleander bush, another highly toxic plant
from the same family.
Cerbera odollam tree is known by a number of vernacular
names depending on the region. These are: othalanga maram in the
Malayalam language used in Kerala, India; kattu arali in the adjacent
state of Tamil Nadu; famentana, kisopo, samanta or tangena
in Madagascar; and pong-pong, buta-buta, bintaro or nyan
in southeast Asia.[2]
The kernels of C.
odollam contain cerberin, a potent alkaloid toxin
related to digoxin, a poison found in foxglove. The poison blocks the calcium ion channels in heart muscle, causing disruption of the
heart beat. This is most often fatal. Cerberin is difficult to detect in autopsies and its taste can be masked with
strong spices. Therefore it is often used in homicide and suicide in India.
In 2004, a team led by Yvan Gaillard of the Laboratory of Analytical Toxicology
in La Voulte-sur-Rhône, France documented more than 500 cases of fatal Cerbera poisoning
between 1989 and 1999 in the south-west Indian state of Kerala alone.[3]
The seeds also
have a long history as a poison in Madagascar. The poison was responsible for
the death of 2% of the population (3000 people per year, 50,000 per generation)
of the central province of Madagascar. The belief in the genuineness and
accuracy of trial by ordeal
using this poison was so strongly held among all that innocent people suspected
of an offense did not hesitate to subject themselves to it; some even showed
eagerness to subject themselves to the test. On one occasion over 6000 people
died in a single ordeal.[citation
needed] The use of ritual poison in Madagascar was
abolished in 1861 by King Radama II[4]. However, it is believed that
this practice may still occur in remote areas of the island.
Ixora
Ixora is a genus of flowering plants in the Rubiaceae family. It consists of tropical evergreen trees and shrubs and holds around 500 species.[1] Though native to the tropical and subtropical areas throughout the world, its centre of diversity is in Tropical Asia. Ixora also grows commonly in subtropical climates in the United States, such as Florida. It is commonly known as West Indian Jasmine. Other common names include: rangan, kheme, ponna, chann tanea, techi, pan, santan, jarum-jarum, Jungle flame, Jungle geranium, and many more. The plants possess leathery leaves, ranging from 3 to 6 inches in length, and produce large clusters of tiny flowers in the summer. Members of Ixora prefer acidic soil, and are suitable choices for bonsai. It is also a popular choice for hedges in parts of South East Asia, like in Thailand. In tropical climates they flower year round.
Red ixora flowers are commonly used in Hindu worship, as well as in Indian folk medicine.
Mushroom(Fungus)
A fungus ( /ˈfʌŋɡəs/; plural: fungi[3] or funguses[4]) is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds (British English: moulds), as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria. One major difference is that fungal cells have cell walls that contain chitin, unlike the cell walls of plants, which contain cellulose. These and other differences show that the fungi form a single group of related organisms, named the Eumycota (true fungi or Eumycetes), that share a common ancestor (a monophyletic group). This fungal group is distinct from the structurally similar myxomycetes (slime molds) and oomycetes (water molds). The discipline of biology devoted to the study of fungi is known as mycology, which is often regarded as a branch of botany, even though genetic studies have shown that fungi are more closely related to animals than to plants.
Abundant worldwide, most fungi are inconspicuous because of the small size of their structures, and their cryptic lifestyles in soil, on dead matter, and as symbionts of plants, animals, or other fungi. They may become noticeable when fruiting, either as mushrooms or molds. Fungi perform an essential role in the decomposition of organic matter and have fundamental roles in nutrient cycling and exchange. They have long been used as a direct source of food, such as mushrooms and truffles, as a leavening agent for bread, and in fermentation of various food products, such as wine, beer, and soy sauce. Since the 1940s, fungi have been used for the production of antibiotics, and, more recently, various enzymes produced by fungi are used industrially and in detergents. Fungi are also used as biological pesticides to control weeds, plant diseases and insect pests. Many species produce bioactive compounds called mycotoxins, such as alkaloids and polyketides, that are toxic to animals including humans. The fruiting structures of a few species contain psychotropic compounds and are consumed recreationally or in traditional spiritual ceremonies. Fungi can break down manufactured materials and buildings, and become significant pathogens of humans and other animals. Losses of crops due to fungal diseases (e.g. rice blast disease) or food spoilage can have a large impact on human food supplies and local economies.
The fungus kingdom encompasses an enormous diversity of taxa with varied ecologies, life cycle strategies, and morphologies ranging from single-celled aquatic chytrids to large mushrooms. However, little is known of the true biodiversity of Kingdom Fungi, which has been estimated at around 1.5 million species, with about 5% of these having been formally classified.[citation needed] Ever since the pioneering 18th and 19th century taxonomical works of Carl Linnaeus, Christian Hendrik Persoon, and Elias Magnus Fries, fungi have been classified according to their morphology (e.g., characteristics such as spore color or microscopic features) or physiology. Advances in molecular genetics have opened the way for DNA analysis to be incorporated into taxonomy, which has sometimes challenged the historical groupings based on morphology and other traits. Phylogenetic studies published in the last decade have helped reshape the classification of Kingdom Fungi, which is divided into one subkingdom, seven phyla, and ten subphyla.
Bougainvillea
Bougainvillea
They are thorny, woody vines growing anywhere from 1 to 12 meters tall, scrambling over other plants with their spiky thorns. The thorns are tipped with a black, waxy substance. They are evergreen where rainfall occurs all year, or deciduous if there is a dry season. The leaves are alternate, simple ovate-acuminate, 4–13 cm long and 2–6 cm broad. The actual flower of the plant is small and generally white, but each cluster of three flowers is surrounded by three or six bracts with the bright colours associated with the plant, including pink, magenta, purple, red, orange, white, or yellow. Bougainvillea glabra is sometimes referred to as "paper flower" because the bracts are thin and papery. The fruit is a narrow five-lobed achene.
Bougainvillea are relatively pest-free plants, but may suffer from worms, snails and aphids. The larvae of some Lepidoptera species also use them as food plants, for example the Giant Leopard Moth (Hypercompe scribonia).
Use and Cultivation
Bougainvilleas are popular
ornamental plants in most areas with warm climates, including
Ethiopia,
Indonesia,
Aruba, the
Philippines,
Thailand,
Pakistan,
India,
Sri Lanka,
Yunnan, China,
Taiwan,
Vietnam,
Malaysia,
Australia,
Greece,
Spain,
Turkey,
Cyprus,
Singapore, the
Mediterranean region, the
Caribbean,
Central America,
Mexico,
South Africa,
Kuwait,
Qatar, the
United Arab Emirates and the southern mainland
United States and
Hawaii.
Locarno in Switzerland, with its mild Mediterranean climate, is famous for its bougainvilleas.
Although it is frost-sensitive and hardy in U.S.
Hardiness Zones 9b and 10, bougainvillea can be used as a houseplant or hanging basket in cooler climates. In the landscape, it makes an excellent hot season plant, and its drought tolerance makes bougainvillea ideal for warm climates year-round. Bougainvillea has a high salt tolerance, which makes it a natural choice for color in coastal regions. As a woody clambering vine, bougainvillea will stand alone and can be pruned into a standard, but it is perfect along fence lines, on walls, in containers and hanging baskets, and as a hedge or an accent plant. Its long arching branches are thorny, and bear heart-shaped leaves and masses of papery bracts in white, pink, orange, purple, and burgundy. Many cultivars, including double flowered and variegated, are
available.
Twenty years after
Commerçon's discovery, it was first published as 'Buginvillea' in
Genera Plantarum by
A.L. de Jusseau in 1789. The genus was subsequently split in several ways until it was finally corrected to 'Bougainvillea' in the
Index Kewensis in the 1930s. Originally, B. spectabilis and B. glabra were hardly differentiated until the mid 1980s when botanists recognized them to be totally distinct species. In early 19th century, these two species were the first to be introduced into
Europe, and soon, nurseries in
France and
England did a thriving trade providing specimens to
Australia and other faraway countries. Meanwhile,
Kew Gardens distributed plants it had propagated to
British colonies throughout the world. Soon thereafter, an important event in the history of bougainvillea took place with the discovery of a crimson bougainvillea in
Cartagena, a Spanish port in the
Mediterranean, by Mrs. R.V. Butt. Originally thought to be a distinct species, it was named B. buttiana in her honour. However, it was later discovered to be a natural hybrid of a variety of B. glabra and possibly B. peruviana - a "local pink bougainvillea" from Peru. Natural hybrids were soon found to be common occurrences all over the world. For instance, around the 1930s, when the three species were grown together, many hybrid crosses were created almost spontaneously in
East Africa,
India, the
Canary Islands, Australia,
North America, and the
Philippines.
Many of today's bougainvillea are the result of interbreeding among only three out of the eighteen
South American species recognized by botanists. Currently, there are over 300 varieties of bougainvillea around the world. Because many of the hybrids have been crossed over several generations, it's difficult to identify their respective origins. Natural mutations seem to occur spontaneously throughout the world; wherever large numbers of plants are being produced, bud-sports will occur. This had led to multiple names for the same cultivar (or variety) and has added to the confusion over the names of bougainvillea cultivars.
The growth rate of Bougainvillea vary from slow-growing to rapid, depending on the particular variety. Bougainvillea tend to flower all year round in equatorial regions. Elsewhere, they are seasonal bloomers. They grow best in somewhat dry, fertile soil. Bloom cycles are typically four to six weeks. Bougainvillea grow best in very bright full sun and with frequent fertilization, but the plant requires little water once established. As indoor
houseplants in temperate regions, they can be kept small by
bonsai techniques. If overwatered, Bougainvillea will not flower and may lose leaves or wilt, or even die from root decay. Bougainvillea can be easily propagated via tip cuttings.
[5]
Symbolism
Various species of Bougainvillea are the official flowers of the island of
Guam;
[6] Lienchiang and
Pingtung Counties in
Taiwan;
Ipoh, Malaysia;
[7] the cities of
Tagbilaran,
Philippines;
Camarillo, California;
Laguna Niguel, California;
San Clemente, California; the cities of
Shenzhen,
Huizhou,
Zhuhai, and
Jiangmen in
Guangdong Province,
China; and
Naha, Okinawa.
Toxicity
The sap of the Bougainvillea can cause skin rashes similar to Toxicodendron species.
Animals
Water Snail Eggs & Water Snails
A freshwater snail is one kind of freshwater mollusc, the other kind being freshwater clams and mussels, i.e. freshwater bivalves. Specifically a freshwater snail is a gastropod that lives in a watery non-marine (freshwater) habitat. The majority of freshwater gastropods have a shell, with very few exceptions. Some groups of snails that live in freshwater respire using gills. Others need to surface to breathe air.
According to present classification efforts, there are about 4,000 species of freshwater gastropods (3,795-3,972).[1]
At least 33–38 independent lineages of gastropods have successfully colonized freshwater environments.[2] It is not possible to quantify the exact number of these lineages yet, because they have yet to be clarified within the Cerithioidea.[2] From six to eight of these independent lineages occur in North America.[3]
2010 taxonomy
The following cladogram is an overview of the main clades of gastropods based on the taxonomy of Bouchet & Rocroi (2005),[4] modified after Jörger et al. (2010)[5] and simplified with families that contain freshwater species marked in boldface:[1] (Marine gastropods (Siphonarioidea, Sacoglossa, Amphiboloidea, Pyramidelloidea) are not depicted within Panpulmonata for simplification. Some of these highlighted families consist entirely of freshwater species, but some of them also contain, or even mainly consist of, marine species.)
Ants
Ants
are
Ants form colonies that range in size from a few dozen predatory individuals living in small natural cavities to highly organised colonies that may occupy large territories and consist of millions of individuals. Larger colonies consist mostly of sterile wingless females forming castes of "workers", "soldiers", or other specialised groups. Nearly all ant colonies also have some fertile males called "drones" and one or more fertile females called "queens". The colonies sometimes are described as superorganisms because the ants appear to operate as a unified entity, collectively working together to support the colony.[5]
Ants have colonised almost every landmass on Earth. The only places lacking indigenous ants are Antarctica and a few remote or inhospitable islands. Ants thrive in most ecosystems and may form 15–25% of the terrestrial animal biomass.[6] Their success in so many environments has been attributed to their social organisation and their ability to modify habitats, tap resources, and defend themselves. Their long co-evolution with other species has led to mimetic, commensal, parasitic, and mutualistic relationships.[7]
Ant societies have division of labour, communication between individuals, and an ability to solve complex problems.[8] These parallels with human societies have long been an inspiration and subject of study. Many human cultures make use of ants in cuisine, medication, and rituals. Some species are valued in their role as biological pest control agents.[9] Their ability to exploit resources may bring ants into conflict with humans, however, as they can damage crops and invade buildings. Some species, such as the red imported fire ant, are regarded as invasive species, establishing themselves in areas where they have been introduced accidentally.[10]
Development and Repoduction
The life of an ant starts from an egg. If the egg is fertilised, the progeny will be female (diploid); if not, it will be male (haploid). Ants develop by complete metamorphosis with the larva stages passing through a pupal stage before emerging as an adult. The larva is largely immobile and is fed and cared for by workers.
Food is given to the larvae by trophallaxis, a process in which an ant regurgitates liquid food held in its crop. This is also how adults share food, stored in the "social stomach". Larvae may also be provided with solid food such as trophic eggs, pieces of prey, and seeds brought back by foraging workers and the larvae may even be transported directly to captured prey in some species.
The larvae grow through a series of moults and enter the pupal stage. The pupa has the appendages free and not fused to the body as in a butterfly pupa.[47] The differentiation into queens and workers (which are both female), and different castes of workers (when they exist), is influenced in some species by the nutrition the larvae obtain. Genetic influences and the control of gene expression by the developmental environment are complex and the determination of caste continues to be a subject of research.[48] Larvae and pupae need to be kept at fairly constant temperatures to ensure proper development, and so often, are moved around among the various brood chambers within the colony.[49]
A new worker spends the first few days of its adult life caring for the queen and young. She then graduates to digging and other nest work, and later to defending the nest and foraging. These changes are sometimes fairly sudden, and define what are called temporal castes. An explanation for the sequence is suggested by the high casualties involved in foraging, making it an acceptable risk only for ants who are older and are likely to die soon of natural causes.[50][51]
Most ant species have a system in which only the queen and breeding females have the ability to mate. Contrary to popular belief, some ant nests have multiple queens while others may exist without queens. Workers with the ability to reproduce are called "gamergates" and colonies that lack queens are then called gamergate colonies; colonies with queens are said to be queen-right.[52] The winged male ants, called drones, emerge from pupae along with the breeding females (although some species, such as army ants, have wingless queens), and do nothing in life except eat and mate.
Most ants are univoltine, producing a new generation each year.[53] During the species-specific breeding period, new reproductives, females and winged males leave the colony in what is called a nuptial flight. Typically, the males take flight before the females. Males then use visual cues to find a common mating ground, for example, a landmark such as a pine tree to which other males in the area converge. Males secrete a mating pheromone that females follow. Females of some species mate with just one male, but in some others they may mate with as many as ten or more different males.[7]
Mated females then seek a suitable place to begin a colony. There, they break off their wings and begin to lay and care for eggs. The females store the sperm they obtain during their nuptial flight to selectively fertilise future eggs. The first workers to hatch are weak and smaller than later workers, but they begin to serve the colony immediately. They enlarge the nest, forage for food, and care for the other eggs. This is how new colonies start in most ant species. Species that have multiple queens may have a queen leaving the nest along with some workers to found a colony at a new site,[54] a process akin to swarming in honeybees.
A wide range of reproductive strategies have been noted in ant species. Females of many species are known to be capable of reproducing asexually through thelytokous parthenogenesis [55] and one species, Mycocepurus smithii, is known to be all-female.[56]
Ant colonies can be long-lived. The queens can live for up to 30 years, and workers live from 1 to 3 years. Males, however, are more transitory, being quite short-lived and surviving for only a few weeks.[57] Ant queens are estimated to live 100 times longer than solitary insects of a similar size.[58]
Ants are active all year long in the tropics, but, in cooler regions, they survive the winter in a state of dormancy or inactivity. The forms of inactivity are varied and some temperate species have larvae going into the inactive state, (diapause), while in others, the adults alone pass the winter in a state of reduced activity.[59]
Behaviour and Ecology
Communication
Ants
communicate with each other using pheromones, sounds, and touch.[60]
The use of pheromomes as chemical signals is more developed in ants than in
other hymenopteran groups. Like other insects, ants
perceive smells with their long, thin, and mobile antennae. The paired antennae
provide information about the direction and intensity of scents. Since most
ants live on the ground, they use the soil surface to leave pheromone trails
that may be followed by other ants. In species that forage in groups, a forager
that finds food marks a trail on the way back to the colony; this trail is followed
by other ants, these ants then reinforce the trail when they head back with
food to the colony. When the food source is exhausted, no new trails are marked
by returning ants and the scent slowly dissipates. This behaviour helps ants
deal with changes in their environment. For instance, when an established path
to a food source is blocked by an obstacle, the foragers leave the path to
explore new routes. If an ant is successful, it leaves a new trail marking the
shortest route on its return. Successful trails are followed by more ants,
reinforcing better routes and gradually identifying the best path.[61]
Ants use
pheromones for more than just making trails. A crushed ant emits an alarm
pheromone that sends nearby ants into an attack frenzy and attracts more ants
from farther away. Several ant species even use "propaganda
pheromones" to confuse enemy ants and make them fight among themselves.[62]
Pheromones are produced by a wide range of structures including Dufour's
glands, poison glands and glands on the hindgut, pygidium, rectum, sternum, and
hind tibia.[58] Pheromones also are exchanged, mixed
with food, and passed by trophallaxis,
transferring information within the colony.[63]
This allows other ants to detect what task group (e.g., foraging or nest
maintenance) to which other colony members belong.[64]
In ant species with queen castes, when the dominant queen stops producing a
specific pheromone, workers begin to raise new queens in the colony.[65]
Some ants
produce sounds by stridulation, using the
gaster segments and their mandibles. Sounds may be used to communicate with
colony members or with other spieces.
Learning
Many animals can learn behaviours by imitation, but ants may be the only group apart from mammals where interactive teaching has been observed. A knowledgeable forager of Temnothorax albipennis will lead a naive nest-mate to newly discovered food by the process of tandem running. The follower obtains knowledge through its leading tutor. Both leader and follower are acutely sensitive to the progress of their partner with the leader slowing down when the follower lags, and speeding up when the follower gets too close.[83]
Controlled experiments with colonies of Cerapachys biroi suggest that an individual may choose nest roles based on her previous experience. An entire generation of identical workers was divided into two groups whose outcome in food foraging was controlled. One group was continually rewarded with prey, while it was made certain that the other failed. As a result, members of the successful group intensified their foraging attempts while the unsuccessful group ventured out fewer and fewer times. A month later, the successful foragers continued in their role while the others had moved to specialise in brood care.[84]
Cultivation of food
Most ants are generalist predators, scavengers, and indirect herbivores,[19] but a few have evolved specialised ways of obtaining nutrition. Leafcutter ants (Atta and Acromyrmex) feed exclusively on a fungus that grows only within their colonies. They continually collect leaves which are taken to the colony, cut into tiny pieces and placed in fungal gardens. Workers specialise in related tasks according to their sizes. The largest ants cut stalks, smaller workers chew the leaves and the smallest tend the fungus. Leafcutter ants are sensitive enough to recognise the reaction of the fungus to different plant material, apparently detecting chemical signals from the fungus. If a particular type of leaf is found to be toxic to the fungus, the colony will no longer collect it. The ants feed on structures produced by the fungi called, gongylidia. Symbiotic bacteria on the exterior surface of the ants produce antibiotics that kill bacteria introduced into the nest that may harm the fungi.[88]
Navigation
Foraging ants travel distances of up to 200 metres (700 ft) from their nest [89] and scent trails allow them to find their way back even in the dark. In hot and arid regions, day-foraging ants face death by desiccation, so the ability to find the shortest route back to the nest reduces that risk. Diurnal desert ants of the genus Cataglyphis such as the Sahara desert ant navigate by keeping track of direction as well as distance travelled. Distances travelled are measured using an internal pedometer that keeps count of the steps taken [90] and also by evaluating the movement of objects in their visual field (optical flow).[91] Directions are measured using the position of the sun.[92] They integrate this information to find the shortest route back to their nest.[93] Like all ants, they can also make use of visual landmarks when available [94] as well as olfactory and tactile cues to navigate.[95][96] Some species of ant are able to use the Earth's magnetic field for navigation.[97] The compound eyes of ants have specialised cells that detect polarised light from the Sun, which is used to determine direction.[98][99] These polarization detectors are sensitive in the ultraviolet region of the light spectrum.[100] In some army ant species, a group of foragers who become separated from the main column sometimes may turn back on themselves and form a circular ant mill. The workers may then run around continuously until they die of exhaustion.[101] Such wheels have been observed in other ant species, notably when a group has fallen into or been overcome with water, whereby the group rotates in a partially submerged circle on the surface of the water. The behavior could allow survival of a brief flooding.
Relationship with humans
Ants perform
many ecological roles that are beneficial to humans, including the suppression
of pest populations
and aeration of the soil. The use of weaver ants in citrus cultivation in southern
China is considered one of the oldest known applications of biological control.[9] On the other hand, ants may become
nuisances when they invade buildings, or cause economic losses.
In some parts
of the world (mainly Africa and South America), large ants, especially army ants, are used as surgical sutures. The wound is pressed together
and ants are applied along it. The ant seizes the edges of the wound in its
mandibles and locks in place. The body is then cut off and the head and
mandibles remain in place to close the wound.[142][143][144]
Some ants of
the family Ponerinae have toxic venom and are of medical importance. The
species include Paraponera clavata (Tocandira) and Dinoponera
spp. (false Tocandiras) of South America [145]
and the Myrmecia ants of Australia.[146]
In South Africa, ants are used to help harvest rooibos (Aspalathus linearis), which are
small seeds used to make a herbal tea. The plant disperses its seeds widely,
making manual collection difficult. Black ants collect and store these and
other seeds in their nest, where humans can gather them en masse. Up to
half a pound (200 g) of seeds may be collected from one ant-heap.[147][148]
Although most
ants survive attempts by humans to eradicate them, a few are highly endangered.
Mainly, these are island species that have evolved specialized traits. They
include the critically endangered Sri Lankan relict ant
(Aneuretus simoni) and Adetomyrma venatrix
of Madagascar.[149]
It has been
estimated by E.O. Wilson that the
total number of individual ants alive in the world at any one time is between
one and ten quadrillion (short scale). According to this estimate, the
total biomass of all
the ants in the world is approximately equal to the total biomass of the entire
human race.[150]
Relationships with other organisms
Ants form symbiotic associations with a range of species, including other ant species, other insects, plants, and fungi. They also are preyed on by many animals and even certain fungi. Some arthropod species spend part of their lives within ant nests, either preying on ants, their larvae, and eggs, consuming the food stores of the ants, or avoiding predators. These inquilines may bear a close resemblance to ants. The nature of this ant mimicry (myrmecomorphy) varies, with some cases involving Batesian mimicry, where the mimic reduces the risk of predation. Others show Wasmannian mimicry, a form of mimicry seen only in inquilines.[114]5]
Aphids and other hemipteran insects secrete a sweet liquid called, honeydew, when they feed on plant sap. The sugars in honeydew are a high-energy food source, which many ant species collect.[116] In some cases the aphids secrete the honeydew in response to ants tapping them with their antennae. The ants in turn keep predators away from the aphids and will move the them from one feeding location to another. When migrating to a new area, many colonies will take the aphids with them, to ensure a continued supply of honeydew. Ants also tend mealybugs to harvest their honeydew. Mealybugs may become a serious pest of pineapples if ants are present to protect mealybugs from their natural enemies.[117]
Myrmecophilous (ant-loving) caterpillars of the butterfly family Lycaenidae (e.g., blues, coppers, or hairstreaks) are herded by the ants, led to feeding areas in the daytime, and brought inside the ants' nest at night. The caterpillars have a gland which secretes honeydew when the ants massage them. Some caterpillars produce vibrations and sounds that are perceived by the ants.[118] Other caterpillars have evolved from ant-loving to ant-eating: these myrmecophagous caterpillars secrete a pheromone that makes the ants act as if the caterpillar is one of their own larvae. The caterpillar is then taken into the ant nest where it feeds on the ant larvae.[119]
Fungus-growing ants that make up the tribe Attini, including leafcutter ants, cultivate certain species of fungus in the Leucoagaricus or Leucocoprinus genera of the Agaricaceae family. In this ant-fungus mutualism, both species depend on each other for survival. The ant, Allomerus decemarticulatus, has evolved a three-way association with the host plant, Hirtella physophora (Chrysobalanaceae), and a sticky fungus which is used to trap their insect prey.[120]
Lemon ants make devil's gardens by killing surrounding plants with their stings and leaving a pure patch of lemon ant trees, (Duroia hirsuta). This modification of the forest provides the ants with more nesting sites inside the stems of the Duroia trees.[121] Although some ants obtain nectar from flowers, pollination by ants is somewhat rare.[122] Some plants have special nectar exuding structures, extrafloral nectaries that provide food for ants, which in turn protect the plant from more damaging herbivorous insects.[123] Species such as the bullhorn acacia (Acacia cornigera) in Central America have hollow thorns that house colonies of stinging ants (Pseudomyrmex ferruginea) who defend the tree against insects, browsing mammals, and epiphytic vines. Isotopic labelling studies suggest that plants also obtain nitrogen from the ants.[124] In return, the ants obtain food from protein- and lipid-rich Beltian bodies. Another example of this type of ectosymbiosis comes from the Macaranga tree, which has stems adapted to house colonies of Crematogaster ants.
Many tropical tree species have seeds that are dispersed by ants.[125] Seed dispersal by ants or myrmecochory is widespread and new estimates suggest that nearly 9% of all plant species may have such ant associations.[126][127] Some plants in fire-prone grassland systems are particularly dependent on ants for their survival and dispersal as the seeds are transported to safety below the ground. Many ant-dispersed seeds have special external structures, elaiosomes, that are sought after by ants as food.[128]
A convergence, possibly a form of mimicry, is seen in the eggs of stick insects. They have an edible elaiosome-like structure and are taken into the ant nest where the young hatch.[129]
Most ants are predatory and some prey on and obtain food from other social insects including other ants. Some species specialise in preying on termites (Megaponera and Termitopone) while a few Cerapachyinae prey on other ants.[89] Some termites, including Nasutitermes corniger, form associations with certain ant species to keep away predatory ant species.[130] The tropical wasp Mischocyttarus drewseni coats the pedicel of its nest with an ant-repellant chemical.[131] It is suggested that many tropical wasps may build their nests in trees and cover them to protect themselves from ants. Stingless bees (Trigona and Melipona) use chemical defences against ants.[89]
Flies in the Old World genus, Bengalia (Calliphoridae), prey on ants and are kleptoparasites, snatching prey or brood from the mandibles of adult ants.[132] Wingless and legless females of the Malaysian phorid fly (Vestigipoda myrmolarvoidea) live in the nests of ants of the genus Aenictus and are cared for by the ants.[132]
Fungi in the genera Cordyceps and Ophiocordyceps infect ants. Ants react to their infection by climbing up plants and sinking their mandibles into plant tissue. The fungus kills the ants, grows on their remains, and produces a fruiting body. It appears that the fungus alters the behaviour of the ant to help disperse its spores [133] in a microhabitat that best suits the fungus.[134] Strepsipteran parasites also manipulate their ant host to climb grass stems, to help the parasite find mates.[135]
A nematode (Myrmeconema neotropicum) that infects canopy ants (Cephalotes atratus) causes the black coloured gasters of workers to turn red. The parasite also alters the behaviour of the ant, causing them to carry their gasters high. The conspicuous red gasters are mistaken by birds for ripe fruits such as Hyeronima alchorneoides and eaten. The droppings of the bird are collected by other ants and fed to their young leading to further spread of the nematode.[136]
South American poison dart frogs in the genus Dendrobates feed mainly on ants, and the toxins in their skin may come from the ants.[137]
Army ants forage in a wide roving column attacking any animals in that path that are unable to escape. In Central and South America, Eciton burchellii is the swarming ant most commonly attended by "ant-following" birds such as antbirds and woodcreepers.[138][139] This behaviour was once considered mutualistic, but later studies found the birds to be parasitic. Although direct kleptoparasitism (birds stealing food from the ants' grasp) is rare, the birds eat many prey insects that the ants would otherwise eat and thus decrease their foraging success.[140] Birds indulge in a peculiar behaviour called anting that, as yet, is not fully understood. Here birds rest on ant nests, or pick and drop ants onto their wings and feathers; this may be a means to remove ectoparasites from the birds.
Anteaters, aardvarks, pangolins, echidnas, and numbats have special adaptations for living on a diet of ants. These adaptations include long, sticky tongues to capture ants and strong claws to break into ant nests. Brown bears (Ursus arctos) have been found to feed on ants. About 12%, 16%, and 4% of their faecal volume in spring, summer, and autumn, respectively, is composed of ants.[141]
Lumbriculus Variegatus
Lumbriculus variegatus, sometimes known as blackworm (or even California blackworm), is the name given to at least three distinct species of worms which are identical in outward appearance. Until 2009, the species were regarded as one. [1][2]
These species of worms live in shallow water marshes, ponds, and swamps, feeding on microorganisms and organic material. They live throughout North America and Europe.
On average, an adult blackworm can have from 150 segments to 250, each of which has the ability to regenerate into a whole new individual when separated from the rest of the animal; in most populations, this is the primary mode of reproduction, and sexually mature individuals are exceedingly rare - in large areas (including Asia, most of North America and the greater part of Europe) sexually mature individuals have never been found.
Characteristics
Among the characteristics of the genus are a green pigmentation of the anterior end, its two-pointed setae, and its curious reflex escape mechanisms. When touched, Lumbriculus will attempt to escape, either by swimming in a helical ("cork-screw") fashion, or by reversing its body. The escape pattern used depends on where the worm is touched: anterior touch elicits body reversal, whereas posterior touch triggers helical swimming. Lumbriculus has a quick reflex that allows it to use its photoreceptors to escape. The photoreceptors can detect shadows and movement. The posterior end lifts out of the water and forms a right angle. It is then exposed to air and is used to exchange oxygen and carbon dioxide, although this exposes its posterior to its enemies. If the photoreceptors detect a shadow or movement, the posterior rapidly shortens in response to a threat.
Reproduction
Regeneration in L. variegatus follows a set pattern. If the regenerating segment originated less than eight segments from the anterior tip, this amount of segments are regenerated; if, however, the segment was originally from a more posterior position, only eight segments are regenerated. Posterior to the segment, a variable number of segments are regenerated, and the original segment undergoes transformation to become suited to the new, often more anterior position. L. variegatus is presumed to be holarctic in distribution, although in East Asia and North America (and perhaps other places as well) it is probably replaced by the other species of the genus (many of which are known from very small areas; Lumbriculus illex, for instance, is known only from three individuals found in a stream to the North of Vladivostok). Mature Lumbriculus can easily be told apart by a number of genital characters, but as few of the species in the genus ever become sexually mature, it is often difficult to know which species you are dealing with. A physical description of L. variegatus is, to a large extent, valid for the entire genus.
