Chapter 32 Animal Evolution 09 22 2015 Well over 1 million species Probably a million more that are undiscovered Usually insects Eukaryotic heterotrophs Found a new frog in new york city not too long ago Differences between plants and animals 1 can t make their own food a ingestive instead of absorptive 2 deal with nitrogenous waste 3 someway to move bring food in 4 have to reproduce a haploid sperm and haploid egg fuse to form zygote b zygote starts cleavage get back to right cytoplasmic nuclear ratio c forms blastula d grastrulation forming very important germ layers i cells on the outside are the ectoderm ii cells on the inside are the endoderm iii archenteron opening will become gut digestion system iv blastopore animals defined by what this becomes 5 animals don t have cell walls 6 store glucose as glycogen 7 tight junctions desmosomes gap junctions choanoflagellates 2 distinct groupings of animals Parazoa sponges shows evolutionary relationship between choanoflagellates Eumetazoa All other animals 570 ya edicaran fossils first sign of animals 540 525 mya Cambrian explosion major representatives of all invertebrates appeared during this era half of all living species today has representatives a lot of predator prey predation very important in advancing evolution red queen hypothesis appearance of free oxygen hox genes genes important in forming the basis and embryology of things o if you duplicate hox genes you may get different structures on different animals split of animals sponges haven t changes in 600 million years radial v bilateral symmetry radial like a pie or wheel if cut like a pie everyone gets the same thing sessile not very mobile bilateral folds in half and matches up left and right side animals that are going to have sense organs head v tail most mobile diploblastic has only ectoderm and endoderm triploblastic ectoderm endoderm mesoderm three layers from with gastrulation acoelomate no body cavity between gut and body wall pseudocoelomate has a body cavity that is not completely lines with mesoderm mesoderm lines ectoderm but not endoderm space between body wall and gut coelomate has a body cavity where the mesoderm lines the endoderm and ectoderm but still has a space fate of blastopore animals can be defined by this protostome vs deuterostome protostome means mouth first o if blastopore becomes mouth deuterostome means mouth second o if blastopore becomes anus Coelom formation Protostome develops mesoderm from the bottom near the blastopore Deuterostome develops in pockets Cleavage Spiral and determinate cleavage o Protostome o Only one cell can become and embryo o Fate of cells determined at first cleavage o Can t have identical twins Radial and inderminate cleavage o Deuterostome o All cells could potentially become embryos o Early in development cells haven t determined who they are o All 8 cells could become complete organisms can have identical twins Totipotent all wise all knowing Ancestral colonial flagella Radial v bilateral Hormone that helps insects shed Nematodes and arthropods 09 22 2015 09 22 2015