For an explanation, see the main splats page
- Arthropods with more than eight legs form several easily distinguished groups, the main ones being the crustaceans, the millipedes and the centipedes.
- Millipedes make a natural group: they are vegetarians, and they have two pairs of legs to each segment. Because of their diet, they are easy to culture.
- Centipedes make a natural group of venomous carnivores, with one pair of legs on each segment, unlike millipedes, which have two pairs of legs per segment.
- Spiders, scorpions and ticks make a natural grouping, based on their number of legs, but in other ways, they are quite distinct in their behaviour and anatomy.
- Spiders hunt in a variety of ways: orb weavers use a normal 'spider web', but others cast a net over their prey, while others chase their prey down in the open.
- Orb weaver spiders can be kept and observed, so long as they are placed on a frame standing in and over water, where they can make a web, but not escape.
- Some species of spiders, and some strains within species, can be social, grouping together. This is a useful characteristic when spiders arrive in a new place.
- Australian huntsmen spiders arrived in New Zealand in the recent past, and while they are rarely social in Australia, they are commonly social in New Zealand.
- Crustaceans make a natural group that is easy to study: slaters or woodlice can be cultured, and freshwater crustaceans can easily be kept in tanks.
- Charles Darwin used a careful analysis of their anatomy to show that barnacles are not shellfish but arthropods: their tentacles are highly modified legs.
- Insects make a natural grouping, because they all have six legs, and either have four wings, or can be shown to have evolved from four-winged ancestors.
- The changes in insects are called metamorphosis: starting as an egg, an insect larva becomes a pupa which becomes the adult form, called an imago.
- In social insects, it is common for all members of a colony to have exactly the same genes, and for one individual to lay all the eggs on behalf of all of them.
- In social insects, having identical genomes is important, because the actions of the sterile workers still go to improve the survival of their genome.
- The beetles or Coleoptera are a very diverse group of insects, but all of them have elytra, which are modified wings, protecting their flight wings.
- Flies have four wings, but fly with just two, the other two (the halteres) being reduced to a very small size and used for balance in flight.
- The role of the halteres in balance may be demonstrated by removing the halteres from an adult fly, which will then be unable to fly in the normal way.
- Fruit flies can be cultured in the laboratory, and they were commonly used in genetics experiments, because they go through generations very rapidly.
- Mosquitoes are a natural division of the flies, based on their reproduction and feeding patterns, where males feed on plants, females on animals.
- Mosquitoes have three clear stages of development, with the egg, the larva and the pupa in water: mosquito development may be observed in captivity.
- The Hymenoptera (ants, wasps and bees) make a natural grouping: almost all of the Hymenoptera form group nests that have a complex social structure.
- Termites, otherwise called the Isoptera, have a complex social structure, featuring a variety of specialized forms or castes within the nest.
- Butterflies and moths are a natural grouping, but the butterflies and moths cannot be divided naturally on any differences, as the division is not a natural one.
- Butterflies and moths show a variety of adaptations to their environments and predators, including the development of 'fright eye' patterns on their wings.
- Caterpillars have specific food preferences, and females will normally lay eggs on food plants suitable for the caterpillars, for obvious evolutionary reasons.
- The Lepidoptera, the moths and butterflies, are varied in their size and form, they differ greatly in their food choices, and some migrate over long distances.
- Case moths always use local dead plants for their covering, and this can be demonstrated in the laboratory. Some case moths never develop wings.
- Some caterpillars and moths are protected by the toxins they eat, and in some cases, they can even pass this protection on to the next generation.
- Moths pollinate some white, heavily-perfumed flowers at night, and it seems that the flowers have developed these traits specifically to attract the moths.
This file is http://members.ozemail.com.au/~macinnis/scifun/, first created on February 18, 2009. Last recorded revision (well I get lazy and forget sometimes!) was on February 18, 2009.
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