2/17/20 Flashcards
class of Mollusca with a closed circulatory system
class Cepholapoda
method of reproduction used by all of Phylum Mollusca
sexual reproduction
course of Mollusc development
in aquatic species, eggs generally hatch into trochophore larva and then into a veliger larva
trochophore definition and function
ciliated larva (aids in locomotion and feeding)
stage that all molluscs but cephalopods progress into after the trochophore stage
veliger
structures present in veliger larva
beginnings of foot, mantle, and shell
only member of Phylum Mollusca that does not develop into a veliger
class Cepholapoda
general characters of class Gastropoda
about 80,000 species, mostly marine but many freshwater/terrestrial, slow-moving, relatively sedentary, shell as self-defense, cephalized head
developmental process underwent by Gastropods
torsion
torsion process
changing of the position of body parts during development; go from a linear gut with gills in the back to a loopy gut with anus and gills near the mouth
pros of torsion
gills are anterior and can sample water, entire body can be pulled within shell
cons of torsion
anus is right above the head/mouth/gills :/
process underwent by some Gastropods where torsion is reversed during development
detorsion
class of Phylum Mollusca that contains most of Mollusca diversity
class Gastropoda
process in some Gastropods in which the shell is lifted upwards and back to help with balance
coiling
impacts of torsion and coiling on Gastropod structure
internal asymmetry of organs, many “paired” organs are lost on the right side
class of Phylum Mollusca known as Chitons
class Polyplacophora
general characters of class Polyplacophora
about 1000 extant species, generally live in rocky intertidal zones, radula reinforced with iron
structure of class Polyplacophora
dorsal shell made of 7-8 separate plates surrounded by girdle of mantle, gills surround the foot
class of Phylum Mollusca that includes mussels, clams, oysters, and scallops
class Bivalvia
general characters of Bivalves
about 9000 species, mostly marine, have lost cephalization and the radula, filter feeders
method by which Bivalves combine feeding with breathing
suck water in through incurrent siphon and over gills, which extract oxygen and capture food particles on layer of mucus before cilia move food towards labial palps, which then direct food into the mouth
organ in Bivalvia used primarily for digging
foot
muscles in Bivalvia that contract to close the shell
adductor muscles
class of Phylum Mollusca that includes, octopuses, squids, cuttlefish, and nautiluses
class Cephalopoda
general characters of class Cephalopoda
all very intelligent marine predators, strong beaklike jaws, mantle used for jet propulsion, many have long tentacles/arms with suckers
only species of class Cephalopoda with an external shell
nautiluses
species of class Cephalopoda where the shell rests under the mantle
cuttlefish
species of class Cephalopoda where the shell is a thin strip called the “pen”
squids
species of class Cephalopoda that has lost the shell entirely
octopuses
structure of circulatory system in class Cephalopoda
two branchial hearts pump deoxygenated blood to gills, systemic heart pumps oxygenated blood to the rest of the body
reproductive process of class Cephalopoda
separate sexes, no larva stage (direct development), very little parental care (except octopuses)
Phylum united by the trait of a molting cuticle
Phylum Ecdysozoa
Phylum of Ecdysozoa known as horsehair worms
Phylum Nematomorpha
general characters of phylum Nematomorpha
about 320 species, very long and thin, adults are free-living but all juveniles parasitize arthropods (emerge once in water)
Nematomorpha do/don’t have sexual separation
do
Phylum of Ecdysozoa known as roundworms
Phylum Nematoda
general characters of Phylum Nematoda
estimated 1,000,000 species, about half are parasitic, live in every habitat on earth, account for 80% of individual animals on earth
structure of Nematodes
unsegmented, pseudocoelomate, generally small, covered in noncellular cuticle made from collagen, longitudinal muscles, simple morphology (mouth, pharynx, intestine, anus, reproductive organs), anterior nerve ring
free-living Nematodes generally go through ____ molts before adulthood
four
“model” organism of Nematoda
C. elegans
