BSC 116 Lecture Notes - Lecture 10: Parazoa, Gastrovascular Cavity, Scyphozoa

• School: University of Alabama
• Department: Biological Sciences
• Course: BSC 116
• Professor: Phillip Harris

Document Summary

Introduction to animal diversity and early animal evolution: Multicellular organisms occur in several clades: not the same as colonial. Multicellular diversity: unicellular protists- 83,000 spp, plants- 288,000 spp, fungi- 100,000 spp, vertebrates- 59,000 spp. Animal- multicellular heterotrophs: no cell walls: collagen (protein) for support, many animals have. Muscle cells- contractile cells to do generation motion. Nerve cells- conduct electrical impulses: characteristic reproduction and developmental processes, asexual reproduction occurs, but it is less common, sexual reproduction typical. Typically with small flagellated sperm and large egg. Sperm enters micropyle of the egg --> fertilization: zygote develops into gastrula. First few hours following fertilization of an egg cell. Gastrulation- invagination of blastopore to form the beginning of the gut. Direct development- offspring looks like a little version of the parent: ex. mammals, some insects. Indirect development- young offspring (larvae) morphologically/ecologically different than the adult: most got through metamorphosis, ex. butterflies, some mollusks.