BIOL 111 Lecture Notes - Lecture 17: Osteichthyes, Actinistia, Lungfish

• School: McGill University
• Department: Biology
• Course: BIOL 111
• Professor: Rudiger Krahe

Document Summary

Biol 111 lecture 17 fishes precious & movement to land: tetrapods. Lecture date/time: nov 5th, 2015 / 10:35-11:25 am. 2 types of bony fish: ray-finned & lobe-finned. Thought to be extinct 65 mya, fossils going back 410 mya. 1938: found at south african fish market. Devonian droughts (~400 mya) shallow inland seas, swamps, ponds, low dissolved o2. Increased competition in water, crowding in small pools. New food resources on land (ex. arthropods, plants) Differences in land & water as relevant to life: Gases diffuse faster in air than water. Circulatory system in fish: 2 chambered heart, blood-oxygenated gills, single-circuit circulation relatively low pressure required (see image); when swimming, water helps the blood flow in fish. Involve changes in volume of thoracic cavity. Boyle"s law: high volume = low pressure, (fewer molecules per unit time hit sides) Gasses move from high pressure to low pressure. ^done by diaphragm (and ribs) which cause changes in volume of thoracic cavity.