Lec 6/7 part A Flashcards
Protostomia taxonomic composition
Most invertebrates
Deuterostomia taxonomic composition
Echinoderms, hemichordates and chordates
Fate of blastopore of protostomia
Becomes mouth, second opening becomes anus
Deuterostomia fate of blastopore
Becomes anus; second opening becomes mouth
Diagnostic features
Characteristics that can identify members of a clade
Synapomorphy
A derived feature shared by members of a taxonomic group. It is homologous and inherited from a common ancestor
Homology
Homologous structures are ones that evolved from a common ancestral structure, though they may look different
Similarity of topology example
Where the humerus is relative to other arm bones
Similarity of detailed morphology example
Humeral head is convex
Similarity of neural innervation example
Diaphragm innervated by the phrenic nerve
Similarity of embryonic development example
The process of cell growth and differentiations to form the eyes
Analogy definition
Analogous structures are ones that evolved from adaptations to similar environments
Similar expressions to analogy
Convergent evolution and homoplastic
Chordate characteristics
Notochord
Spinal chord
Pharyngeal slits
Post-anal tail
Endostyle
Notochord
Still rod of soft tissue supporting the body axis
Transformed into vertebral centra in most vertebrates
Spinal cord
Dorsal hollow nerve cord
Pharyngeal slits
Ancestrally used for feeding, transformed into gill slits in fish, never fully develop in tetrapods
Post anal tail
Tail that extends behind the anus
Endostyle
Organ on the floor of the pharynx that secretes mucus and the hormone thyroxine; transformed into thyroid gland in vertebrates
Ancestral feeding mode of chordates
Filter-feeding
Filter feeding
Water is drawn in through the mouth and expelled through the pharyngeal slits, any food particles being filtered out and trapped in the mucus produced by the endostyle
Cilia (tentacle like structures)
Drive movement of food and water in chordates
Close relatives of vertebrates
Cephalochordata
Urochordata
Cephalochordata
Small marine filter-feeding animals, somewhat fish like
Possess all give diagnostic features of chordates
Muscle blocks and fin propel swimming while notochord provides stiffness
Benthic on sea floor
Having distinct larvae and adult stages
