BIO SCI 94 Lecture 14: Chapter 33: Intro to Animals

• School: UC-Irvine
• Department: Biological Sciences
• Course: BIO SCI 94
• Professor: Robin Bush

Document Summary

The radiation of animals began around the cambrian explosion. All animals are eukaryotes that share key traits. Multicellular, lack cell walls but have extensive extracellular matrix. Heterotrophs obtain carbon compounds they need from other organisms. All animals other than sponges have neurons and muscle cells. Animals are the only multicellular heterotrophs on the tree of life that ingest their food before they digest it. Animals are the largest eating machines (herbivores, carnivores, detritivores) The first important insight is that animals are a monophyletic group. Multicellularity appears to have originated in a sponge-like animal. Both choanoflagellates and sponges are sessile, meaning they live permanently attached to a substrate. Recent research shows that some sponges have true epithelium- a layer of tightly joined cells that covers the interior/exterior surface of the animal. Sponges are distinguished in part by the type the of spicules they produce (stiff spikes of silica or calcium carbonate that provide structural support to ecm.