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Home >>Zoology Dictionary >> Balance - Bioluminescene
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Balance - A function of the inner ear.
Baleen - (=Whalebone) Name given to the plates of keratin that hang from the upper jaws of the toothless whales. The plates filter out the small crustaceans on which the whales feed.
Ball and Socket Joint - A joint such as the hip or shoulder joint that allows movement in any direction.
Basement Membrane - The thin, usually structureless membrane on which epithelial cells rest.
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Bastard Wing - That part of a bird's wing formed by the first finger. It plays an important part in the flight so some birds.
Bats - (See Chiroptera).
Bee - An insect of the super family Apoidea of the order Hymenoptera. Most species are solitary but some the familiar bumblebees and honeybees are social and live in large colonies. There is normally only one mated female the queen in each colony and she is tended by workers who are all sterile females. The queen does nothing but lay eggs. Bees feed on pollen and nectar and they are very important pollinating agents.
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Their mouthparts are finely adapted to sucking up nectar from flowers but they also have biting jaws which they use in constructing the combs. Other parts of the body are specialised for collecting pollen the hairs on the body are feathery and collect the pollen grains which are then combed off by the legs and transferred to 'pollen baskets' on the hind legs.
Honeybee workers construct sheets or combs of cells made of wax and these combs hang vertically in the nesting space which is often a hollow tree, although with domestic bees of course, it is the hive. There are two main types of cell worker cells about 1/5th inch across and slightly large drone cells. Worker cells predominate and the eggs. Worker cells predominate and the eggs that the queen lays in them develop into worker bees. The queen lays special unfertilised eggs in the drone cells and these develop into male bees or drones. There are usually a few hundred drones in a colony, compared with thousands of workers. Every now and then the workers construct large flask shaped cells. Fertilised eggs are laid in them, the larvae are given special treatment by the workers.
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They develop into fertile females of which one will take over the colony after mating with a drone. The original queen dies or, if she is young she goes off with a swarm of workers to found a new colony. Pollen and honey are also stored in the cells of the combs. Honey is nectar that has been acted upon by the bees and from which much of the water has been removed. Both honey and pollen are used to feed the young bees and as a reserve food the young bees and as a reserve food supply for when the weather is too bad to go out.
The workers perform a number of different tasks in the colony, usually graduating from looking after the young to comb building and other domestic work and then to foraging for food. The honeybees have developed a wonderful way of telling each other where there is a good source of food. When a bee has found a rich source of nectar it returns to the colony and 'dances' either outside or inside the nest on the combs. The Austrian biologist Karl von Frisch was the first to study the dances and to discover how they convey information. If the nectar source is within about 100 yards of the nest the returning bees perform what is known as the 'round dance', running round in circles, first one way and then the other. Other bees follow the dance and then set out from the hive in all directions searching for the nectar.
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When the nectar source is more than about 100 yards from the nest the bees perform the 'waggle dance' which takes the form of a figure of eight. If the dance is performed on a flat surface in the open, the 'straight run' of the dance points towards the food.
Other bees note the angle between the run and the sun and then fly off in the right direction. More often, however, the dance is performed on the vertical combs inside the hive. In this case, the angle between the vertical and the straight run of the dance equals the angle between the sun and the food and the bees can still fly in the right direction. The waggle dance so called from the way in which the bee waggles her abdomen while performing it also tells the other bees how far the food is. The further the food, the slower the dance. The bees thus know how far to fly and a what direction. Having arrived in the indicated area, their sight and sense of smell help them to locate the nectar. An inborn sense of time enables the bees to allow for the change in the position of the sun during the day and so they can always find their way about.
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The bees sting is actually a modified egg laying apparatus. The actual sting is barbed and although it can be withdrawn from other insects, it cannot be withdrawn from human skin. After stinging the bee can free herself only by leaving the whole stinging apparatus behind and this normally results in her death. Because the sting is a modified egg layer, only the females can sting.
Although the honeybee colony described here is perennial, going on from year to year, bumblebee colomes are annual affairs. Only the mated queens survive the winter and they have to build the first cells of the new nest in Spring.
Beetle - Insect of the order Coleoptera.
Benthos - Term used to cover organisms living on the sea floor as opposed to those swimming and floating in the water. Includes sea-anemones, starfishes, molluscs, and many others. (See Nekton; Plankton).
Bilateral Symmetry - The arrangment of an organism in such a way that there is only one plane of division that will give two similar halves. Most free living animals are bilaterally symmetrical, with the plane of symmetry running from front to back and from dorsal side to ventral side.
Bile - Secretion of the vertebrate liver which is passed to the intestine where it aids in the digestion of fats. It also contains various waste products which are ejected with the faeces.
Binary Fission - Simple division into two.
Binocular Vision - In many animals the eyes are in the side of the head. Each eye has a distinct field of view, and vision is said to be monocular. But others (birds such as owls, and primates, for example) have binocular vision. The eyes are in the front of the head and their fields of view overlap. The brain interprets the two slightly different sets of signals that it receives from the eyes as one composite picture.
The nerve fibres from the right half of each retina pass to the right side of the brain. Those from the left halves pass to the left side of the brain. Presumably fibres from corresponding parts of each retina pass to the same part of the brain. The stimulation of two corresponding parts of each retina results in a single sensation, thus the combination of the two retinal images produces a single picture. When we 'look cross eyed' at something the images of an object do not fall on corresponding parts of each retina. We thus see everything in duplicate.
It is possible to judge distance when using only one eye, but it can easily be shown that the use of two eyes together increases the speed and accuracy of this operation if a pencil is held vertically in one hand at arm's length. After closing one eye attempts are made to bring the tip of the index finger quickly from the side of the body to the tip of the pencil. If the experiment is then repeated with both eyes open it can be seen how much greater is the precision with which the tip of the pencil can be located. The eyes of man lie about an inch and a half to two inches apart so that a pencil tip (or any other object for that matter) is seen from two slightly different angles. This enables the position of an object to be judged with accuracy.
Many animals with their eyes placed at the sides of the head judge distance by continually moving the head from side to side so that an object is viewed first with one eye and then with the other. A hen, for example, does this when pecking in the grass for grit of edible food materials.
Binomial System of Nomeniclature - The system of naming animals and plants whereby each type of organism has two latin names. The first is the generio name and is spelt with a capital letter. The second is the specific name, spelt with a small letter. The great Swedish naturalist Linnaeus, was the first to use this system on a wide scale. Each species has its own specific name but several closely related species may be grouped in one genus and share one generic name. E.g. the large white butterf1y is Pieris brassicae and the related small white is Pieris papae. It is normal procedure to write scientific names in italics.
Biochemistry - Study of the chemical processes going on in the cells and tissues.
Biological Control - The use of one organism to control the numbers of another usually a pest. Guppies, for example, are used to keep down mosquitoes by feeding on their larvae
Bioluminescence - Light production by living organisms. Nearly all the main groups of animals contain lightproducers-protozoans, sponges, corals, jellyfish, worms, clams, snails, squids, shrimps, centipedes, insects, and fishes provide examples. Perhaps the most familiar are the flefies and glow-worms.
Several species of protozoans are brightly luminous and so numerous that, when disturbed, they light up the surface of the sea. Noctiluca often occurs hear the shore in the surface of the sea. An night, as the breakers crash on to the beach, they appear to burst into flame. In a similar way the wake of a boat may be marked out as a ribbon of sparkling light.
Several bristle worms are luminous. Odontosyllis, swarms prior to spawning. Males and females are attracted to each other by the exchange of light signals. They begin to swarm at the surface between two and three days after a full moon. The males are attracted to the surface by the strong and continuous greenish glow produced along the entire length of the female worms. The males emit short flashes of light. Sperms and eggs are discharged into the water amidst this illuminated confusion.
Many shrimps and prawns have lantern like photophores. A few can also release clouds of luminous slime from special glands. This lighted 'smoke screen' no doubt baffles pursuers in much the same way as the wriggling cast off tail of a lizard. The photophores of shrimps and prawns occur on some of the legs and on parts of the body. Perhaps the pattern they make serves for recognition purposes.
Photophores are best developed in the squids and their relatives, and in fishes. Each photophore consists of a number of light producing cells, a ref1ector, a lens, and an on-off 'switch'. The light emitted is of varying colour. It is possible that the differing arrangements or the photophores distinguish between the sexes or indicate the stage of maturity that the squids have reached.
Heteroteuthis, a small deep water squid living in the Mediterranean instead of shooting out a cloud of ink, as do most other squids when escaping from enemies, produces a luminous cloud round itself.
Most of the luminous fishes live in moderately deep water a few in the abyss. The photophores are usually arranged in rows. A deep sea angler fish has on top of its head a long lure, the luminous tip of which hangs just above its mouth. Prey are attracted by the light and so fall victim to the fish. Certain East Indian fishes have special organs beneath the eye: They are pockets containing bacteria. Bacteria and other light continuously, but the fishes have a shutter mechanism whereby they can either conceal the light or display it.
Famous luminous insects are the glow worms and fireflies. In New Zealand the larvae of a certain fly live on the ceilings of caves. Each glows and spins a web of luminous silk with which to trap food. The ceilings glow as though covered in thousands of tiny hanging chandeliers. The glow worm of Europe is a wingless female beetle (not a worm!) that lives in grass and in hedgerows. Pale green light emitted by photophores on the lower hind part of the abdomen attracts males flying nearby.
Pairing in fireflies depends on the exchange of light signals. The pattern of the signals differs from one species to another. In one species the male emis short flashes at regular intervals. After the pause by a response from the female. There are several such exchanges of signals prior to pairing.
The light produced by living organisms is often referred to as cold light for very little heat is evolved during its production. Measurements indicate that nearly one hundred per cent of the energy produced is released as light (an ordinary electric light bulb is only about 10% efficient!).
The chemical reaction involved is a modification or sidebranch of the reactions that proceed in every living cell. It is essentially the same in all cases so far investigated and, like other 'living' reactions, it is promoted by an enzyme. This enzyme is called luciferase. In the presence of oxygen and an organic compound rich in phosphate (adenosine triphosphate or A.T.P.), luciferase promotes the oxidation of luciferin. This causes the production of light. For each molecule of luciferin that is oxidized, one packet or quantum of light energy is released. The chemical structure of luciferin has been established and it has been synthesized. The luciferase molecule is thought to be a protein chain made up of about one thousand amino acid molecules.
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