Biology 3484A/B Lecture Notes - Cambrian Explosion, Sea Anemone, Convergent Evolution
24 Dec 2012
School
Department
Course
Professor
Document Summary
These are six-footed animals with three pairs of walking legs. Hexapod/insect is a monophyletic group within the arthropoda. A hexapod (insect) is an arthropod with 3 body regions head, thorax, and abdomen (synapomorphy). The head is sensory and it has compound eyes, one pair of antennae, and mouthparts. The thorax has three segments and is used for locomotion. There are three pairs of legs (synapomorphy), with one pair attached to each segment of the thorax. The thorax also has two pairs of wings (this is a synapomorphy for derived insects). The first pair of wings is attached to the second segment of the thorax and the second pair of wings is attached to the third segment of the thorax. The abdomen contains the major internal organs and is involved in reproduction. Animalia (metazoan) evolution major events: eukaryotic cells were present 2bya (proterozoic). Animal fossils were present 630mya and they are relatives of today"s jellyfish and sea anemone.
