Animals For Kids (2)
Vertebrates are animals that have a spine or spinal column, additionally referred to as vertebrae. Of specific word are 10 full specimens of extinct animals; Great Auk alca impennis (and egg), Passenger Pigeon Ectopistes migratoria (2, a mount and a skeleton), Dodo Raphus cucculatus (skeleton), Huia Heteralocha acutirostris (2 mounts, 2 skins), Thylacine Thylacinus cynocephalus (mount) and a semi-fossilised egg of an Elephant Bird Aepyornis maximus.
Comparison of the numbers of IAS-threatened vertebrates with the numbers of vertebrates threatened by different elements revealed that the IAS menace is concentrated in a subset of nations and that IAS are not a very powerful contributor to the number of species that are threatened globally ( figure 3 ). We distinguished two clusters of countries.
Mating with unrelated or distantly related members of the same species is generally thought to offer the advantage of masking deleterious recessive mutations in progeny 50 (and see Heterosis ). Vertebrates have developed numerous diverse mechanisms for avoiding shut inbreeding and selling outcrossing fifty one (and see Inbreeding avoidance ).
Many marine invertebrates are characterized by a specific sort of development e.g. both lecithotrophic or planktotrophic (see Jon Gienger’s weblog post, Planktotrophy versus lecithotrophy ). Interestingly, Aeolidia papillosa veligers hatching from the same egg capsule could be polytypic: some launched as yolk-laden lecithotrophic larvae, and others as yolk-free planktotrophic larvae (Williams, 1980).
Invertebrates have two primary body plans : one is the radial symmetry plan (a round shape organized around a central mouth, similar to the way in which spokes radiate out from the hub of a wheel), which incorporates animals who spend their grownup lives mounted in one place; and the bilateral symmetry plan (proper and left halves that mirror each other and sometimes have a particular front and back end).