BIOL 227 Lecture Notes - Lecture 8: Craniate, Agnatha, Swim Bladder
3 May 2016
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Document Summary
Homology similarity in at least two characters in different taxa due inheritance from a common ancestor. There are at 3 least other ways homology may be understood (1) the cladistics perspective 2 or more species with similar characters, perseumably inherited from a common ancestor (2) the morphological perspective two species with similar characters. General homologous characters of primitive bilaterians e. g. triploblasty and coelom spaces arise early in development, using that middle-derived tissue and space to make various worms with derived body plans. A binocular organization of diversity examining the fact of similarity using different systems: hierarchical classification or homology. Juvenile ascidian (a tunicate class) features are common to early development of all chordates. As an adult, an ascidian tunicate draws in water through an incurrent siphon, filtering food particles. The short-lived, free- swimming larvae has chordate characteristics. The least derived living craniate lineage is the myxini, or the hagfishes.
