17 Flashcards
Ecdysozoans?
One of the Protostomes two major clades
•nematodes and arthropods
Synapomorphies: shedding of the cuticle and exoskeletons
Nematodes?
Ecdysozoan, roundworms.
They flow through gut. Their interiors are pseudocoelomate and unsegmented (body divided into different parts)
The most important model organism in Ecdysozoans?
C. elegans?
Why are c. Elegans so important as a model organism?
Few number of cells, simplicity in nervous system, and transparent, quick reproduction, and exhibit behaviours. Useful for neurological research.
Arthropods are sister to?
Nematodes
Arthropods?
They have body plans formed from segments that can remain separate or fuse.
Synapomorphies: Bent appendages
Flexibility and modularization of these segments and appendages that has allowed for independent development and evolution of regions and appenda in different lineages.
Chelicerates?
•Chelicerates (spiders and scorpions): they have chelicerae, a pair of appendages on the head used as mouthparts to grab but not chew prey
Myriopods?
Millipedes and centipedes. Millipedes have two pairs of legs for every body segment and vegetarians. Centipedes have one pair of legs per body segment and carnivores
Trilobites?
One of the most successful animals during their period, went extinct during the Permian mass extinction. The first animals to clearly see
Pancrustaceans?
A clade containing crustacean and insecta.
Arthropods contain what major clades? 4•
•Trilobites
•Chelicerates
•Myriapods
•Pancrustaceans
First animals to fly about and what were?
350 million years ago, insects
How many years ago did different organisms evolved to fly from now? 3•
•Pterosaurs: 200 Mya
•Feathered dinosaurs and birds: 165 Mya
•Mammals: 50 Mya
Are insect flight wings modified walking limbs?
No, they are actually completely new appendages.
Deuterostomes?
One of Bilateria two major clades
In Deuterostomes vs protostomes, how do the cephalized central nervous system differ?
Cephalized central nervous system runs through the dorsal (back) part of the body in Deuterostomes while in the ventral (front) part of the body in protostomes.
Outgroup of Deuterostomes?
Echinoderms
Echinoderms?
Include starfish, brittle stars, crinoids, sea urchins, and sea cucumbers. They are sister to Chordates but lack a head. They have bilaterally symmetrical larvae, but as adults, they are radially symmetric.
Synapomorphy: pentaradial symmetry, 5-part symmetry and water vascular system.
Water vascular system?
Hydraulic system to move around and feed. They have tiny muscles to move water into the tube feet to move water along.
Deuterostomes characteristics?
Starfish: predators
•Sea urchins: grazers (no arms) special structure:Aristotle’s lantern
•Brittle stars: scavengers
•Crinoids: attached to stalk as juveniles, free swimming as adults
•Sea cucumbers: scavengers, secondarily bilateral.
Synapomorphies: radial symmetry as adults, water vascular system with tube feet.
