BIOL 152 1st Edition Lecture 12Outline of Last Lecture - Animal Diversity Outline of Current Lecture - Animal Body PlansCurrent Lecture- Invertebrates Animal Body Plans Grade - group of animals that share the same level of organizational complexity- Not necessarily equivalent in meaning with clade- Animal body plans exhibit:2. Symmetry3. Tissue layers4. Internal cavities5. Development1. Body symmetry and cephalization Asymmetrical - such as spongesRadial symmetry - such as oral/aboral Bilateral symmetry - such as cephalization 2. Tissue layersSponges lack true tissuesTissue layers form through the process of gastrulationConcentric germ layers form tissues and organsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Animals with two embryonic tissue layers are diploblasts: endoderm and ectodermAnimals with three embryonic tissue layers are tripleoblast: endoderm, mesoderm, and ectoderm- Ectoderm → outer covering and forms the Central Nervous System- Endoderm → digestive system and is associated with the formation of organs- Mesoderm → formation of muscles and other organs3. Body cavity: Animals are triploblastic, but not all animals are triploblastic Fluid-filled space separating the digestive tract from the outer body wall‘True’ coelom forms from mesodermPseudocoelom forms from blastocoel and is fully functional- It is gained and lost several times in the course of animal evolutionFunctions of the coelom- cushion suspended organs - hydro elastic skeleton against which muscles work - allows internal organs to move and grow independently of the outer body wall4. Mode of DevelopmentProtostome and deuterostome developmentThree features distinguish these modes1. Cleavage: affected by how the mitotic spindle forms- Protostome – eight celled – spiral and determinate - Dueterstome – eight celled – radial and intermediate 2. Coelom formation: origin of mesoderm “pocketing”- Protostome – schizocoelous – solid mass of mesoderm splits and forms the coelom- Dueterstome – enterocoelous – folds of archenteron form the coelom 3. Gastrulation: fate of the first pore formed- Protostome – mouth develops from blastopore - Dueterstome – first opening becomes anusAnimal Phylogenetic Tree35 Phyla – relationships debatedA clade represents the ancestors and offspring Two current hypotheses- Morphological- MolecularPoints of agreement between the morphological and molecular phylogenetic tree: - common ancestor – colonial flagellate- sponges are basal- radiata are basal in the Eumetazoa (true animals)- most animals belong to Bilateria- vertebrates and others are deuterostomesPoints of disagreement between the morphological and molecular phylogenetic tree:- relationships among bilaterians- there are only two main clades in morphology tree- there are three main clades in molecular tree- protostomes are broken up into ecdysozoa and
View Full Document
Unlocking...