unit test (platyhelminthes + mollusca)

which phylum had the first true heads ? (cephalization)

platyhelminthes

what kind of symmetry to flatworms have ?

bilateral

how do flatworms move ?

muscle contractions + cilia

what percent of flatworms are parisitic ?

80%

how many species of flatworm are there ?

20,000

what is the symbiotic algae that some flatworms contain ? (which makes them a brightly colored green)

zoochlorella

how many tissue layers do flatworms have and what is this called ?

3; triploblastic

nerves that run horizontally across flatworm

transverse nerves

nerves that run vertically down flatworm

nerve cords

head region of a flatworm contains…

sense organs + nervous tissue (brain)

how many eyespots do flatworms have ?

2

what body systems do flatworms NOT have?

respiratory, skeletal, circulatory

how do flatworms breathe ?

pores for oxygen diffusion

flatworms are acoelomates (which defines them from other groups) what does this mean ?

they lack a body cavity between the body wall + digestive tract

what kind of digestive system do flatworms have ?

incomplete

where is the mouth located on a flat worm?

posterior end — not at the head

what structure is food carried through to get to the gastrovascular cavity (in flatworms) ?

pharynx

tube cells (flatworms)

special ciliated cells that move liquid

do flatworms have an anus

no

flame cell (flatworms)

like a kidney, it removes waste through filtration. has a flagella. connected to tube cell.

flatworms are usually ____ (reproductive term)

hermaphroditic

flatworm asexual reproduction includes:

fragmentation + budding

flatworm sexual reproduction includes:

self-fertilization + hypodermic impregtation

hypodermic impregtation

flatworms try to stab eachother with genitals to get one pregnant before the other

what are the three classes in phylum platyhelminthes (flatworms)

turbellaria, trematoda, cestoda

which flatworm class is this ?

• free-living and NOT parasitic

turbellaria

which flatworm class is this ?

• parasitic; internal parasites to mollusks + vertebrates

• flukes

trematoda

which flatworm class is this ?

• parasitic tapeworms

• live in digestive tracts of vertebrates

cestoda

mollusca is ___ % of all marine organisms

23

how many species of mollusca

85,000

how many tissue layers do mollusks have, what is this called, and what are they?

3 layers, triploblastic, endoderm, mesoderm, ectoderm

what kind of symmetry to mollusks have?

bilateral

what is a coelom? (mollusks are coelomates)

hollow fluid filled cavity located between the digestive tract cavity + body wall

mantle

muscular tissue surrounding gills and organs, secretes/makes the shell

foot

used for sensory perception and locomotion

radula

ribbon of small teeth made of chitin that is used for feeding

what are the 3 defining features of mollusks?

mantle, foot, radula

mollusca is a phylum. what are the four classes within it?

gastropoda, polyplacophora, bivalvia, cephalopoda

what does gastropoda mean if the word was broken down?

stomach foot

what is the largest class of mollusks?

gastropoda

all gastropods have…

a coiled shell around a visceral mass

examples of gastropods:

snails, limpets, abalones, nudibranchs, pteropods

what is torsion?

body is twisted 180 within the shell, which positions anus above head

gastropod nervous system contains…

a ganglia (cluster of nerves) and two major nerve cords

what are the 2 major nerve cords of a gastropod nervous system and what do they do?

visceral for internal organs, pedal for foot

what kind of circulatory system do gastropods have?

open

what is the fluid similar to blood that mollusks have ?

hemolymph

what does nudibranch mean

naked gills

what is the only gastropod to lose their external shell (so they have an internal shell)

nudibranchs

how do nudibranchs eat cnidarians?

they concentrate nematocysts in cerata

what does polyplacophora mean ? (this class includes chitons)

many plates to bear

what is the most defining feature of polyplacophora?

eight dorsal plates

how does polyplacophora eat ?

iron radula to scrape algae

what animals are in class bivalvia?

mussels, clams, oysters, scallops

class bivalvia are filter feeders so they do not have…

a head or radula

part of shell that was formed when the animal was a juvenile; the knob/highest point on the back side

umbo

hinge ligament

connects the valves; opens and closes them

adductor muscles (things that are hard to get off; leave scar)

holds shell shut

what structures allow water to enter and leave a bivalve ?

incurrent + excurrent siphons

palps (where is it/what does it do)

located in mantle cavity, used for feeding, has ciliated grooves that collect organic material

what kind of digestive system does a bivalve have

complete

how many pairs of ganglia do bivalves have ?

3

what animals do class cephalopoda include ?

squids, octopus, cuttlefish, nautilus

how do cephalopods move?

jet propulsion

what are chromatophores ?

special skin cells that allow the organism to change color

which cephalopod does NOT have ink ?

nautilus

octopuses do NOT have tentacles. they have arms

yes

how does jet propulsion work ?

water enters the mantle cavity and is quickly expelled out of the siphon

what kind of digestive system do cephalopods have ?

complete

digestive system of a cephalopod begins in the buccal mass which contains…

beak, pharynx, radula, salivary glands

where is food stored in cephalopods ?

in the crop

what do the caecum + digestive glands do (cephalopods)

help break down food + nutrients

cephalopods use ____ to percieve touch

chemoreceptors

the cephalopod circulatory system is ___ and contains ____… (this can be used to distinguish from other mollusks)

closed; real blood

what are the hearts cephalopods have?

one systemic heart and two branchial hearts

the branchial hearts are known as …

gill hearts

what do cephalopods have in their blood instead of hemoglobin?

hemocyanin

in cephalopods small gills =

faster speed

what are the three subclasses within class cephalopoda ?

nautiloidea, coleoidea, ammonoidea

order nautilida is in subclass nautiloidea and contains the nautilus

yes

what makes the nautilus different from other cephalopods ?

it has a shell used for buoyancy

what are the four orders in subclass coleoidea ?

octopoda, teuthida, vampyromorpha, sepiida

order octopoda contains what animal

octopuses

hectocotylus arm

only in males; used to transfer sperm to females

octopuses do not have a shell, but they do have…

a shell rudiment — small leftover structure made of calcium carbonate

octopuses can squeeze through any hole larger than their ___

beak

order teuthida contains what animal

squid

how many tentacles do squid have and what are they used for ?

2 tentacles for seizing prey

what is the pen of a squid ?

internal shell

order vampyromorpha contains what animal

vampire squid

vampire squids are NOT actually squids

yes

where do vampire squids live ?

in the tropics near the equator but still very far down

what is a cuttlebone

internal shell used for buoyancy

cuttlefish are similar to squids —- they have 8 arms + 2 tentacles but cuttlefish have…

a little frill along the outside

what type of reproduction do mollusks use ?

sexual reproduction

bivalves use ___ fertilization and cephalopods/gastropods use ___ fertilization

external, internal

cephalopods have spermatophores which are

packets of sperm delivered to females

links for labeling diagrams:

https://www.purposegames.com/game/gastropoda-snail-internal (gastropod)

https://www.purposegames.com/game/bivalve-clam-diagram-game (bivalve)

which mollusk belongs to order sepiida ?

cuttlefish