BISC 121Lg Lecture 17: Bio 121 Lecture 17
Document Summary
Petromyzontida (lampreys) have developed vertebrae, oldest vertebrates: marine and freshwater, ectoparasitic organisms, live on other organisms. Eat prey"s blood and other tissues: larvae look like lancelets. There are ~52,000 species of vertebrates, including the largest organisms in earth"s history. Vertebrates have a wide range of differences. Dorsal fin stabilizer, lift from pectoral and pelvic fins, buoyancy from oils. Intestinal spiral valve to increase surface area to increase rate of nutrient absorption. Sharp vision with no color, olfaction from paired nostrils, detect electrical fields, use lateral line to detect vibrations. Internal fertilization and young are born either from eggs hatched outside the mother, inside the mother, or as live young. Closely related to sharks but live a different lifestyle and hold a different ecological niche. Flattened bottom dweller that crush mollusks and crustaceans in their jaws. Whiplike tail that can have venomous barbs to protect themselves. Large pectoral fins used like wings to swim.
