Overview of the Invertebrates Group
Which species don't have backbones or bony skeletons?
Did you know that 97% of all animal species have no back bone? I'm Aubrey for About.com. Today I'm going share a few distinctive characteristics of invertebrates, using information from animals.about.com.Invertebrates are are multi-cellular animals, that don't have backbones or bony skeletons. There bodies produce structure and support by other means. Insects, for example, often develop a protective exoskeleton. Crustaceans such as lobsters and crabs have hard outer shells for protection.Invertebrates were the first animals to evolve. Many scientists believe the invertebrates came about from the evolution of heterotrophic, or food eating, microorganisms.30 different animal groups fall within the invertebrate category. A few examples include: spiders, bugs, slugs, snails, barnacles, and starfish. Many of the world's parasites are invertebrates. Ticks, and leeches are both examples of invertebrate parasites. They often find nourishment from more than one host over the course of a lifetime and go through many life cycles.Invertebrates often live in colonies. They often remain in these colonies for the majority of their lives, helping to divide up labor, protect each other and ensure reproduction. The simplest animal, the sponge, is an example of an invertebrate.Many invertebrates go through a process of metamorphosis at some phase in their life cycle. Caterpillars for example go through this form of transformation, triggered by hormones, before they become butterflies.Thank you for watching, for more information on mammals or other animal groups, go to: education.about.com.
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