Class Notes (837,188)
Canada (510,157)
Biology (Sci) (2,472)
BIOL 111 (283)

Mollusca and Nervous System

3 Pages
Unlock Document

Biology (Sci)
BIOL 111
Irene Gregory- Eaves

18/10/11 Mollusca: 2 largest phylum - Terrestrial/aquatic - High diversity: morphology, modes of nutrition, reproduction - Bilaterally symmetrical, trioblastic - Coelomate protostomes - Trochophore larcae (marine) - Variation on an ancestral molluscan Morphology: 1. Foot: often used for locomotion, sometimes have cilia, secretes 2. Mantle: secretes CaCO3 layer 3. Mantle cavity: allows water to com in and out, breathe through modified gills 4. Visceral mass: a. Radula: series of corrugated, toothed, serrated to rasp across the ground to feed, predation, Diversity: 1. Polyplacophore: many plates – series of places over lapping, not as hard as snail shells - Oldest: burgess shale (520-560 million years old - Multiple gills - Omnivorous, but not predatory Ex. Chiton: - Large muscular foot - Ability to roll into ball - Gills located in mantle gills 2. Bicalvia: two valves - Reduced of head some have vestigial eyes or brain - Hinged shells can open and close - Enlargement of foot: used to burrow through the ground and anchorage - Siphons: in current/out current: filter feeders, pulls out small nutrient - Enlarged gills - Sessile in adult phase - Broadcast spawners - Vissel thread associated with foot (secreted by foot) - If under sedement can extend siphon up to filter water Ex scallop: - Lined with eyes: can detect motion and light, fly through the water 3. Gastropoda: - Most diverse within mollusca (terrestrial marine, fresh water, deep ocean, in trees) - Long fossil record in Burgess Shale 18/10/11 - Can be shelled (snails), shelless (slugs, nudibranchs) - Hebivorous, omnivorous - Dioecious or hemaphradidic – but can only produce sperm of eggs at one time - Mouth and anus are close each other - Mantle cavity right above head - Torsion: body/shell orientation spin left of right: elongation of shell occurs Ex. Cone snail: have harpoon that comes out the front = radula modified to be toxic Ex. Nudibranch: exclusively marine: gills = specialized filaments accorss bodies Ex. Land snails: image forming eyes on tips of tentacles, elongated feet 4. Cephalopoda: head foot – have multiple arms/tentacles on their heads - Shell is often absent, or present in the body – reduced shells, enlarged head for skeleton like thing - Subdivided foot = arms or tentacles
More Less

Related notes for BIOL 111

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.