Bio Lab 4 (Mollusca) Flashcards
phylums that are being studied
Mollusca and phylum annelida
coelomate
both mollusks and annelids have a circular body cavity called a coelom. mesoderm is in two places, see diagram
coelomates are divided into
protostomes (GI tract develops mouth first then anus) and deuterostomes (GI develops anus first then mouth)
protostomes
include phylum molusca, annelida and arthropoda
Have well developed nervous, circulatory, excretory reproductive and digestive systems
deuterostome
include echinodermata (starfish), and vertebrates (hemichordate and chordata)
mollusca
- mantle that secretes a calcium shell
- Their coelom is often just a small chamber surrounding the heart
- Open circulatory system
- Body plan: includes a visceral mass of organs, a muscular foot used for locomotion, a calcium shell, and a mantle that secretes the shell (may aid in respiration),
- Have unique rasping tongues called radula
- cephalization (has a head)
Annelida
- Coelomates
- very serially segmented into repetitive segments but has parts of system in each (not yet fully developed) divided by a septa!
-Complete digestive tract
Have bristles called setae on each segment that help with crawling
-closed circulatory system - has cephalization
Mollusca are
mollusks
annelida are
segmented worms
Class Polyplacophora
- commonly called chitons
- has 8 shell plates (poly) on the dorsal
- have a little segmentation
-radula, a horny-toothed organ in the mouth, scrapes food (algae) from rocks.
Mollusca
class gastropoda
gastropods (gastro = stomach, poda = foot) (snails, nudibranchs and slugs)
- different species have different
shells
- have a radula and a spiral shell due to unequal growth rate in snails but no shell in nudibranchs and slugs
Mollusca
class bivalvia
Clams, oysters, scallops, and mussels are bivalves (bi = two, valve = door or shell) having a dorsally hinged shell in two parts
- filter water
- held together by adductor muscles and an umbo (elbow)
- are filter feeders
- have a foot that has more organs inside and is used for locomotion/ anchoring
- Mollusca
Class Cephalopoda
- Head-foot, cuttle fish, squid, and octopus
- Lack a radula, but have a parrot-like beak for tearing flesh
- Siphons used for respiration and jet propulsion, free-swimming
- Foot modified into tentacles,
- the nautilus shell iS NOT A GRSTROPOD
closed circulatory system - cephalized and segmented (septa divide)
- some segments are specialized, and each one has brittles called setae
Mollusca
Class Polychaeta
poly = many, chaeta = setae) filled with poison
- very segmented
- have fleshy appendages called parapodia
These appendages help in filter feeding, locomotion, reproduction, holding and capturing prey
Class Oligochaeta
EARTHWORM
- have a lip called the prostomium
- first body segment is called the peristomium
- closed circulatory system
- ventral spinal chord
- clitellum is closer to the head than the anus
- few setae
- have a GI system, brain
- have a nephridium for getting rid of wastes
Class Hirudinea
leeches. Leeches lack setae
- Carnivores and blood sucker
- Three slicing teeth
- Salivary gland is anti-coagulant
- release packets of sperm called spermatophores into female
IN LAB,
dissected earthworms and clam
cephalization
formation of a head that has the sense organs. usually in the front of the body
mantle secretes the
shell for protection
mollusks that don’t have shell
octopus, slug and one more
deuterostomes
GI tract develops anus to mouth
protostomes
develop GI from mouth to anus
Gastropoda animals
snails, nudibranchs and slugs
how do bivalves filter water
Trap food particles in gills and water moves into the shell via incurrent siphon and out of the shell via excurrent siphon
how does bivalve open and close
Powerful “adductor” muscles close the shell, (“add” the two shells together)
Hinge and umbo cause the shells to open when the adductor muscles relax
cephalopod skeleton
Circular and longitudinal muscles work against a fluid filled coelom acting as an hydrostatic skeleton.
what do Polychaeta’s parapodia help with?
filter feeding, locomotion, reproduction, holding/capturing prey
how do oligocaheta get rid of waste
Paired nephridia for fillration pulling in body through a nephrostome and wastes out a nephridiopore
good folding for increase in SA?
typhlosole arising from the dorsal wall of an oligochaete. doubles the SA
muscles in a earthworm vs. nematode
earthworm has circular and longitudinal muscles
dorsal vs ventral cross section of earthworm
- dorsal has the typhlosole, the nephridia open out of the ventral side. also ventral nerve chord
body shape of leeches vs oligochaete and polychaete?
dorsoventrally flattened vs others
leeches have setae?
no
are leeches as segmented as others?
no
what function do suckers serve other than feed on leech?
locomotion
