Lab Exam 3 Flashcards
what does Mollusca mean in Latin?
soft-bodied
what animals does Mollusca include
chitons, snails, slugs, clams, oysters, squids, octopuses, cuttlefish, and others
where do molluscs live
marine and fresh waters, and various terrestrial habitats
three major regions of the molluscan body plan
- muscular foot
- visceral mass
- mantle
muscular foot
used for locomotion
mantle
a fleshy tissue attached to the visceral mass that secretes the shell
shell
usually made of calcium carbonate
mantle cavity
between the mantle and visceral mass, which contains the gills and the openings of the digestive, excretory, and reproductive systems
are molluscs diploblastic or triploblastic
triploblastic
mollusc symmetry
bilateral
do molluscs display cephalization
yes
what kind of body cavity
coelom
are molluscs deuterostomes or protostomes
protostomes
what type of cleavage
spiral cleavage
what kind of larva
trochophore
four classes of molluscs
Polyplacophora, Bivalvia, Gastropoda, Cephalopoda
Polyplacophora common name
chitons
Bivalvia common name
bivalves
Gastropoda common name
snails and slugs
Cephalopoda common names
squid, nautilus, and octopus
where do chitons live
marine, worldwide, from cold waters to the tropics
how many seperate shell plates do chitons have
7-8
what is the first shell plate called in chitons
anterior valves
what is the last shell plate called
posterior valve
what are the chiton’s plates encircled by
the mantle
what is the mantle in chitons also known as
the girdle
how do chitons get food off the ground
with a radula
how does the foot function in chitons
suctions them to the rock surface during wave actionq
where are the chitons’ heads and mouths
below the girdle and shell plates, can’t be seen from the dorsal surface
where is the mouth cavity on chitons
runs around the animal between the mantle and the foot and contains the repiratory gills
are chitons monoecious or dioecious
dioecious
how does fertilization occur in chitons
in the water
development in chitons
zygote develops into the trochophore larva and metamorphosizes into a young chiton
how many shells does the chiton have?
one
do chitons have a radula?
yes
what is the function of the chiton’s radula?
to scrape food off the ground
where are the gills found in chitons?
the mantle cavity
where do bivalves live?
both marine and freshwaters
how many valves compose the bivalve’s shell
two
how do bivalves feed
filter feeding
what structures are bivalves missing
head, radula
special characteristics of bivalve foot
can extend beyond the shell and move then animal when burrowing in the sand
how are the two valves hinged in bivales
hinged on the dorsal surface and held together by an elastic hinge ligament
elastic hinge ligament function
to hold together the two valves of a bivalve’s shell
umbo
swollen area near the hinge of bivalves, and is the oldest part of the shell
are bivalves dioecious or monoecious
dioecious
bivalves gonads function
produce the gametes and release them into the water through the excurrent aperture
is fertilization internal or external in bivalves
external
bivalve development
fertilized egg develops into a trochophore larva, which is then transformed into a veliger larva (with bivalve shells) and then into the adult shell
where do gastropods live
moist areas on land, or are marine
what is the shell for gastropods like
single coiled shell (or shell is absent) covering the visceral mass
how do gastropods feed
herbivores, feeding with a radula
nudibranches (naked gills) class
Gastropoda
body torsion
the visceral mass of the animal is rotated 180 degrees to one side during development, producing an animal with its anus more or less above its head
which class displays body torsion
gastropods
where is the mouth located in gastropods
ventral to the head with an internal radula
where is the mantle cavity located in gastropods
just within the shell above the head
where is the pneuomostome located in gastropods
right below the shell and leads into the mantle cavity (or lungs in land molluscs)
where are the eyes located in gastropods?
at the end of the tentacles
what is the function of the mantle cavity?
respiration
what is the function or the pneumostome?
communicates the lung and mantle cavities
what do all cephalopods have in common?
the head/foot is modified into tentacles/arms and a siphon
where do cephalopods live
marine
are cephalopods monoecious or dioecious
dioecious
how do cephalopods feed
they are active predators
what are the fins on cephalopods called
lateral fins
what is the visceral mass covered with in cephalopods
thickened mantle, which forms a loose-fitting collar about the neck
special characteristics of eyes in cephalopods
complex, highly advanced eyes that can form clear images
convergent evolution example
vertebrate and cephalopod eyes
cephalopod appendages
8 arms with rows of suckers, and 2 longer tentacles which are used to capture prey
where does the mouth lie in cephalopods
within the circle of arms and contains beaklike jaws
where is the siphon lie in cephalopods
projects under the collar on the posterior side
how does the siphon work
it is used as “jet-propulsion” locomotion in cephalopods
chromatophores
pigment producing cells throughout the mantle of squids and octopuses
which animals contain chromatophores
squids and octopuses
which side is the siphon on?
posterior side
what are the tentacles used for?
grasping prey
what does convergent evolution mean?
two groups of animals evolved to both have the same trait
what is the purpose of the chromatophores?
to help octopuses and squids blend in to their surroundings
what is the pen?
the shell of the squid that is reduced and embedded into the mantle tissue
where is the pen found
it is the apex of the collar of the squid’s mantle
what is the function of the numerous chambers within the nautilus shell?
to pump air and water in and out of its shell, creating jet propulsion to thrust itself backwards and to make turns
primary characteristics of phylum mollusca
visceral mass, mantle, head-foot region, radula, trochophore and/or veligar larva stages
primary characteristics of class Polyplacophora
-elongated, dorsally flattened body with a reduced head
-radula present
-shell in 7-8 plates
-seperate sexes
-example: chitons
primary characteristics of class Bivalvia
-body enclosed in a two-lobed mantle
-shell is composed of two valves connected at the dorsal hinge
-cephalization is reduced
-no radula
-seperate sexes
-filter feeders
-example: clams
primary characteristics of class Gastropoda
-asymmetrical body
-coiled univalve shell
-well developed head with a radula
-visceral mass torsion
-examples: snails and slugs
primary characteristics of class Cephalopoda
-shell often reduced or absent (except in nautili)
-head well developed with cephalization
-foot modified into appendages (arms and tentacles) and siphon
-seperate sexes
-example: squids
main characteristics of Annelids
-protostomes
-complete digestive tract
-ventral nerve cord
segmented body parts
-closed circulatory system
-high degree of cephalization
-excretory system
metamerism
external and internal serial repetition of body parts and organs
what did the development of metamerism lead to
tagmatization
are annelids hermaphroditic?
yes
most significant evolutionary feature of annelids
metamerism
first advantage of metamerism
it facilitates a more efficient locomotion
second advantage of metamerism
lessens the impact of bodily injury
third advantage of metamerism
leads to the development of tagmatization
how does metamerism facilitate a more efficient locomotion?
by having the coelom divided into segments by the septa, a hydrostatic skeleton is created which provides a rigid structure for muscles to push (contract) against
how does metamerism lessen the impact of bodily injury?
by having multiple backup organs in each segment if one segment fails
what is tagmatization
the ability to devote certain segments of the body for specialized functions, sensory function, and/or feeding
three classes of annelids
Class Polychaeta, Class Oligochaeta, Class Hirudinida
common name of Polychaeta
clamworms
common name of Oligochaeta
earthworms
common name of Hirudinia
leeches
largest class of annelids
Polychaeta
where do clamworms live
marine locations in burrows in the mud
general external appearance of clamworms
-have a head with sensory structures (eyes and tentacles)
-parapodia bearing numerous setae on each body segment
characteristics of clamworm prostomium
-4 dark eyes
-a pair of small tentacles
-fleshy palps
where is the peristomium located on a clamworm
behind the prostomium
characteristic of peristomium
holds 4 pairs of sensory peristomal tentacles
where is the pharynx usually located on a clamworm
it is usually inverted into the head unless the worm is feeding
characteristics of clamworm pharynx
-large and muscular
-bears many small horny teeth, and a pair of dark pincerlike jaws
where is the mouth located on the clamworm
between the jaws
where are the lateral parapodia located on a clamworm
posterior to the head
what is each parapodium divided into
a dorsal lobe and a ventral lobe
dorsal lobe
notopodium
ventral lobe
neuropodium
what does each lobe of the parapodium have on a clamworm
a bundle of bristles called setae
characteristics of the caudal segment of the clamworm
-lacks parapodia
-bears anus
-bears a pair of sensory cirri
where are new segments added on a clamworm
anterior to the caudal segment
caudal segment
the last segment of the clamworm
how many eyes does Nereis have?
four
how many peristomal tentacles does Nereis have?
eight (four pairs)
where is the nerve cord of the clayworm?
ventral side
what is the function of the parapodia
used for creeping and swimming
what type of coelom do they have
true coelom
where do earthworms live
primarily terrestrial, living in freshwater or damp soil, are usually nocturnal
characteristics of earthworms
-few short setae
-never have parapodia
-cephalization reduced
-monoecious, with no larva stage
how many segments make up the head region in an earthworm
four
what is the first segment in an earthworm called
prostomium
earthworm prostomium
the first segment which is a circular lobe that overhangs the mouth
what is the segment of earthworms called
peristomium
characteristics of the earthworm peristomium
bears the mouth opening, is the second segment
earthworm clitellum
a slightly swollen area (lighter in color) 1/3 of the way down the worm
-used during reproduction
earthworm caudal segment
the last segment
-contains the anus
how does food travel in an earthworm
mouth (by the pharynx) –> esophagus –> crop (storage area) –> muscular gizzard (for grinding and pulverizing) –> intestines (digestion and absorption) –> out anus
earthworm circulatory system characteristics
-closed
-made up of dorsal and ventral blood vessels
-5 aortic arches (hearts) surrounding the esophagus
earthworm excretory system characteristics
-pair of nephridia on the ventral side of each segment
earthworm nephridium characteristics
-begins with a ciliated funnel-shaped nephrostome, which opensinto the anterior segment
-a tubule extends from the nephrostome, into the posterior segment, to the bladder which empties to the outside through the nephridiopore of the posterior segment
earthworm nervous system characteristics
-pair of dorsal cerebral ganglion (on the dorsal side of pharynx)
-leads to a ventral nerve cord
earthworm reproductive system characteristics
-ventral
-lies under the digestive tract
-monoecious
-males have seminal vesicles that contain the testis within them
-females have seminal receptacles which store the sperm of other worms, with ovaries posterior to the seminal receptacles, with a pair of oviducts posterior to the ovaries
what is the function of the seminal receptacles in earthworms?
recieve sperm from the male
what is the function of the crop?
food storage
what is the function of the gizzard?
grinding and pulverizing
where is the nerve cord?
ventral
how many hearts does the earthworm have?
five
what is the function of the clitellum?
produces the cocoon in earthworms and leeches
leech segmentation characteristics
33-34 externally, secondarily divided
leech characteristics
-33-34 annula
-anterior and posterior suckers
-no parapodia or setae
-excrete hirudin
-monoecious
hirudin
blood thinning chemical excreted by leeches
overall characteristics of Class Polychaeta
-free-living, segmented, predacioius worms
-specialized head with sensory structures
-a pair or parapodia bearing numerous setae on each body segment
-no clitellum
-trochophore larva
general characteristics of Class Oligochaeta
-free-living, segmented, primarily terrestrial and freshwater
-live in soil, usually nocturnal
-only have a few short setae, no parapodia
-cephalization reduced
-clitellum present
-monoecious, no larva stage
general characteristics of Class Hirudinida
-free-living, mostly freshwater
-33-34 segments with many annula
-clitellum present
-anterior and posterior suckers
-parapodia and setae absent
general characteristics of arthropods
-triploblastic
-coelomates
-exoskeleton
-jointed appendages
-metamerism
-tagmata
-bilateral
-dorsal brain and ventral nerve cord
main characteristic of arthropod’s circulatory system
open circulatory system
-specialized respiratory structures
specialized arthropod respiratory structures
gills, book lungs, trachea with spiracles
ain characteristic of arthropods
dioecious with internal fertilization with metamorphosiss
how has metamorphosis contributed to arthropod’s success
by reducing competition between the larval and adult form
trilobite tagmata
cephalon, thorax, and pygidium
are trilobite appendages biramous or uniramous
biramous
how many pairs of antennae do trilobite have
one
distinguishing characteristic of chelicerates
-posess a chelicera as the first pair of appendages instead of mandibles
second pair of chelicerate appendages
pedipalps, usually sensory
how many tagmata do chelicerates have
two: the cephalothorax and abdomen
subphylums of Arthropoda
Subphylum Trilobita. Subphylum Chelicerata, Sybphylum Crustacea, Subphylum Myriapoda, Subphylum Hexapoda
classes of Cheliecerata
Class Merostomata, Class Arachida
common name of Trilobita
trilobites
common name of Chelicerata
spiders and horseshoe crabs
main characteristics of subphylum Trilobita
-all extinct
-3 regions: head, thorax, abdomen
-biramous appendages
main characteristics of subphylum Chelicerata
-one pair chelicera
-one pair pedipalps
-four pairs walking legs
-no antenna or mandibles
-2 body regions: cephalothorax and abdomen
main characteristics of class Merostomata
-book gills
-carapace and telson
-mouth ventral and central
main characteristics of sea spider class
-a proboscis
-very small abdomen
-oviger in males
main characteristics of class Arachnida
-chelicerae with fangs
-book lungs
-Malpighian tubules
-can spin silk webs
main characteristics of subphylum Crustacea
-head with a pair of mandibles and two pairs of maxillipeds
-two pairs of antennules
-biramous appendages
-body regions: head and thorax fused into a cephalothorax covered by a carapace, and an abdomen
-compound eyes
main characteristics of subphylum Myriapoda
segmented body with uniramous appendages
main characteristics of class Chilopoda
-dorsoventrally flattened
-each segment contains one pair of legs with maxillipeds modified into venomous fangs
-uniramous appendages
main characteristics of class Diplopoda
-cylindrical bodies
-4 thorax segments with 1 pair of legs while all other segments have 2 pairs of legs
-uniramous appendages
main characteristics of subphylum Hexapoda
-3 body regions: head, thorax, abdomen
-thorax usually divided into 3 sub-regions and usually with 2 pairs of wings
-uniramous appendages
-3 pairs of walking legs
-1 pair of antenna and compound eyes
-metamorphosis
