Get Rid Of House Centipedes
The reason for this is rooted in language. Often, at least for familiar creatures, the very word we use may be adult-specific. A tadpole is, arguably, not a frog. But is a foal not a horse And the same applies in the invertebrate world. A caterpillar is, arguably, not a butterfly (though its genes are identical) but a baby centipede is definitely a centipede.
And 'very many indeed' (sometimes more than 100) in the appropriately named myriapods. Given that there is an excess of legs over what is required for locomotion, surely some could be modified into other things Well, yes, and there are lots of cases where this has clearly happened. Many arthropod mouthparts are smallish paired appendages that have been derived from 'spare' pairs of legs in an ancestor. The centipede's impressive poison claws, which we encountered in Chapter 5, have probably also been derived in this way. However, while this process of divergence from replicated, initially identical structures is an evolutionary reality, we should not feel too complacent about our understanding of it, because although we can explain some features of organisms in this way, we have not yet developed any predictive ability. Centipedes, for example, would appear to have a particular surplus of legs, and yet the 'longest' ones, with 191 pairs, have not specialized any more of them into...
Fascinating as the story is, its relevance outside the insect world is limited. Human embryos do not have imaginal discs buried deep within them nor do frog embryos, despite the fact that they, like flies, are indirect developers and proceed to adulthood via metamorphosis. And even in the arthropod world, many groups - centipedes, for example - do not have equivalents of the fly's imaginal discs. That is why this particular process does not help us, at least on the face of it, to arrive at a general theory of how development works, regardless of the animal that emerges at the end of it. At a deeper level, though, it might help, because all those invisible happenings within each disc, such as the switching on of some genes in some places by the products of other genes, are indeed general, even though the discs themselves are not. However, to get at these happenings, I'm going to move back in time to when the maggot is still an embryo encased
We have used houseflies, honeybees, ants, millipedes, centipedes, hornets, grasshoppers, and small beetles. The fastest results are obtained with honeybees, which may be trapped within 10 minutes. The live, captured insect is put in a container which, in turn, is placed in a freezer for 3-5 minutes. This
The largest number of species in the animal kingdom belongs to the phylum Arthropoda. Members of this phylum, called arthropods, include such animals as spiders, ticks, centipedes, lobsters, and insects. All animals in the phylum have an external skeleton, a segmented body, and jointed appendages. Five major classes divide the phylum Arthropoda. The first two classes include the centipedes and millipedes. These animals have multiple appendages and are able to move efficiently on land. Another class of arthropods is the crustaceans. In these animals, the exoskeleton, hardened with calcium salts, serves as a protective shell. Crabs, shrimp, lobster, and crayfish are crustaceans. The arachnids comprise the fourth class of arthropods. Arachnids have a fused head and thorax and usually have four pairs of legs. Within this group are spiders, ticks, mites, and scorpions.
It makes sense to approach this issue with three distinct questions in a logical order. The first is does developmental bias exist in the real world as well as in my (and others') imagination I am confident that the answer to this question is an unqualified 'yes'. Such an answer is possible on the basis of a single clear example. And one such example, though a rather unusual one, is the fact that all known species of centipedes have odd numbers of leg-pairs (between 15 and 191). Not a single species has an even number. If there were only three species of centipede, we could write this off as being due to chance but since there are in fact about 3000 species, this explanation is clearly untenable.