Biology reading for 4/17/15Cambrian explosion: a wave of animal divarication that occurred during the Cambrian period of the Paleozoic eraBilaterians: a clade whose members have a two-sided or a bilaterally symmetric form and a complete digestive tract, an efficient digestive system that has a mouth at one end and an anus at the otherPredators acquired novel adaptations during the Cambrian Period, for instance forms of locomotion to catch prey.The amount of oxygen on the planet increasedAmphibians and Amniotes: two surviving terrestrial groups of vertebratesBody plan: a particular set of morphological and developmental traits integrated into a functional wholeDorsal: TopVentral: BottomAnterior: FrontPosterior: BackGerm layersEctoderm: the germ layer covering the surface of the embryo. It gives rise to the outer covering of the animal and, to come, the central nervous systemEndoderm: the inner most germ layer, it lines the pouch that forms during gastration and gives rise to the linings to the digestive tractDiploblastic: Animal groups that only have two germ layersMesoderm: the third germ layer. Fills the space between the ectoderm and the endodermTriploblastic: animals that are bilaterally symmetrical and contain all three layersBody cavity: a fluid- or air-filled space located between the digestive tract and the outer body wallCoelom: a body cavity that is formed by tissue derived from mesodermCoelomates: animals with a true coelomPseudocoelom: a body cavity that is formed from mesoderm and endodermPseudocoelomates: Animals that have a pseudocoelomAcocolomates: Animals that lack a body cavitySpiral cleavage: planes of cell division are diagonal to the vertical axis of the embryoDeterminate cleavage: the developmental fate of each embryonic cell very earlyRadical cleavage: characterized deuterostome development. The cleavage planes are either parallel or perpendicular to the vertical axis of the embryo.Indeterminate Cleavage: Each cell produced early by the cleavage division retains the capacity to develop into a complete embryoArchenteron: a blind pouch that is formed by an embryo’s developing digestive tube. It eventually becomes the gutBlastopore: the opening of the archenteron that typically develops into the anus in deuterosomesand the mouth in protostomes- All animals share a common ancestor- Sponges are basal animals- Eumetazoa: a clade of animals with “true” tissues- Most animal phyla belong to the clade BilateriaDeuterostomia, Lophotrochozoa, and Ecdysozoa: Three major clades of bilaterian animalsInvertebrates: animals that lack a backboneVertebrates: Animals that have a backboneLophophore: a crown of ciliated tentacles that function in feedingQuizlet link: