10 chap 16 mollusca

7/28/2019 10 Chap 16 Mollusca

1/29

Mollusca

and

Introduction to Spiralia


2/29

Phylogeny of Protostomes

Protostomia

Bilateria

Spiralia

Deuterostomia

Ecdysozoa


3/29

Ancestry of Mollusca

Protostomia

Spiralia Ecdysozoa

Lophotrochozoa

Platyhelminthes,Rotifera LophophorataEutrochozoa

AnnelidaMollusca


4/29

Trochophore Larvacompare Hickman Fig. 16-6

basis of the term Eutrochozoa

present in many marine mollusks and annelids


5/29

Marine Mollusk Larvaecompare Hickman Fig.s 16-6 and 16-7

Veliger


6/29

Phylum Mollusca Name means soft-shelled nut

2nd largest phylum in number of species Most are free-living and marine

but many clams and snails are freshwater orterrestrial

Feeding habits:

Scrapers and suspension feeders (rarely,carnivores)


7/29

EucoelomateBody Design

Coelom: fluid-filled cavitybetween gut and body wallthat is lined with mesodermalcells (peritoneum).

acoelomate

pseudocoelomate

eucoelomateendodermmesodermectoderm

(muscles, notperitoneum)

peritoneum


8/29

Important Mollusk Features coelom - just the pericardium, a sac around the

heart muscular foot - posterior, ventral, locomotory

mantle - dorsal epidermis that makes the shell also encloses the body in a mantle cavity

ciliated mantle cavity helps with respiration andsometimes feeding

radula - tongue-like scraper used for feeding


9/29

Molluscan Anatomy(chiton; Hickman Fig. 16-9)


10/29

Mollusk Body DesignsHickman Fig.s 16-9, 16-18, 16-31, 16-38


11/29

not presentin Bivalvia

RadulaHickman

Fig. 16-2

motion while feeding


12/29

Mollusca Classesrequired in ZO 110

Bivalvia - clams, mussels, oysters, etc. Polyplacophora - chitons

Gastropoda - snails and slugs Cephalopoda - squid, octopus, nautilus


13/29

Bivalviaclams and mussels

shell of two "valves lateral, ciliated gills for respiration and

filter-feeding

narrow foot for burrowing

head just mouth and labial palps - no radula


14/29

Clam Filter-Feeding FlowHickman Fig. 16-30, 16-31

Pos.

Ant.Dor.

Ven.


15/29

Valuable Bivalvia

many are edible oysters, scallops, blue mussels, clams

river mussels harvested for making seed pearls

symbol of freshwater biodiversity

popular with collectors


16/29

Bivalve PestHickman Pg 343

Dreissena, the zebra mussel


17/29

Polyplacophorachitons

eight dorsal shell plates

slow-moving - foot has strong suction

grazer-scrapers with radula eat algae from rocks between or below

the tides


18/29

Gastropodasnails and slugs

also conchs, limpets, abalones, and sea hares terrestrial, freshwater, or marine

single shell, or none scrape up food or attack prey with radula

most diverse mollusk class > 40,000 named species


19/29

Gastropod Body DesignCampbell Fig. 16.18


20/29

Snail AnatomyHickman Fig. 16-18


21/29

Shell-less GastropodsHickman Fig. 16-22, 16-23


22/29

ConusEats a FishHickman Fig. 16-16


23/29

Class Cephalopodanautilus, squid, octopus

modification of foot, addition of a beak forcarnivory

reduced shell or flotation for swimming

improved respiration, circulation, andneural/behavioral complexity support high

activity levels


24/29

NautilusHickman Fig. 16-36

many tentacles, without suckers

large shell, floated by chambers of gas


25/29

Squid FeaturesCompare Hickman Fig. 16-38

streamlined shape undulating lateral fins

funnel arms & tentacles with

suckers, sometimes poison

Usual direction ofmovement - dorsal


26/29

Giant Squid!

Artituthus can be 30 ft+


27/29

Complex Squid BehaviorHickman Fig. 16-39

shell reduced to pen

mood and camouflage colors

ink for concealment


28/29

OctopusHickman 16-40

8 arms with suckers shell lost, body soft

ink sac


29/29

Pop Quiz 4

1. Term for the hard structure used bycephalopods in feeding: _______

2. Term for the molluscan coelom thatis restricted to the area around theheart: __________

3. Class name for the chitons: ______

10 chap 16 mollusca

Documents