BIOL 371 Lecture Notes - Lecture 25: Thyroid Hormones, Decibel, Salamander
Document Summary
Haikouella, early cambrian shales in china- early vertebrate fossil. Dorsal nerve cord, muscle segments, endostyle, brain but no early jaw. Mouth parts that are partially suction, gill structures, and long and skinny. Only has a dorsal fin and gill slits and sectional mouth. Anadromous- breed in fresh water and migrate to salt water or land and return to freshwater. Think that jaws originated from the gill arches supports. Sharks: heterocercal tail, paired lateral fins, pectoral fins, pelvis fins, and dorsal fin. Accumulate lots of fat- specific gravity (mass per unit of volume) of 0. 8-0. 9 which gives the sharks buoyancy. Contained in the liver and fat is called squalene. Detects water pressure- through the lateral line organs and nerves. Ampullae of lorenzini are pores by the snout and connect to the nervous system. Continuous production of new teeth- foremost set are the active ones with the replacement sets growing behind. Males have claspers and deposit sperm directly in the female.
