clam dissection. clams are: invertebrates- no backbone protostomes- blastopore becomes mouth
TRANSCRIPT
CLAM DISSECTIONKINGDOM ___________
PHYLUM ____________ “Soft”
CLASS ______________ “2 shells”
ANIMALIA
MOLLUSCA
BIVALVIA (Pelecypoda)
NO CEPHALIZATION (No head)
Shell = valve (Bivalves = 2 shells)
Growth rings
Adults = sessile (stay in one place)
SEXUAL REPRODUCTIONSEPARATE SEXES
Male & female clams
Marine (salt water) clams- external fertilizationFreshwater clams- internal fertilization
(sperm enters through siphon)
Other mollusks
GASTROPODS- internal fertilization
Land snails = hermaphrodites
Aquatic snails = 2 separate sexes
CEPHALOPODS- internal fertilization
Separate sexes –
Indirect developmentTROCHOPHORE LARVA Ciliated- can swim
ADULTS-
Sessile = stay in one place
Can put out foot and crawl
GILLS Trap food (PALPS move it forward)
Ridges for more surface area
(like typholosole)
Gas exchange Diffusion moves oxygen & carbon dioxide
across membrane
OPEN CIRCULATION• Blood flows loose inside coelom
and tissue spaces
• Reduced Coelom = pericardial cavity
(space around heart)
PROBLEMS with OPEN CIRCULATION
Less efficient way of moving oxygen & nutrients to muscles (and removing Nitrogen wastes).
High oxygen and low oxygen fluids mix so muscles can’t function as efficiently
DIGESTIVE• Food pulled in through incurrent siphon by
cilia on gills • Food trapped in mucous on gills• Palps move food up and into mouth
esophagus stomach
Digestive gland
Intestine anus
ALL Released into Mantle cavity/ exit via excurrent siphon• Nitrogen waste from kidney • Digestive waste from anus• Sperm or egg (if external fertilization) • Larva (if internal fertilization)