Exam 2 Flashcards
invertebrates
animals that lack a backbone
what level of organization do Porifera have?
cell level
are Porifera symmetrical or asymmetrical?
asymmetrical
do Porifera have germ layers?
no
do Porifera have body cavities?
no
Phylum Porifera general features
-cell level of organization
-asymmetry
-no germ layers
-no body cavities
how do sessile sponges feed (Phylum Porifera)
filter feeding
Porifera definition
pore-bearing (body perforated by many pores)
what are Phylum Porifera skeletons composed of?
spicules
can sponges regenerate?
yes
where do Porifera live?
most marine, some brackish water, few freshwater
how do sponges look?
some are branched, some are standing erect, some are encrusting
sponge cell types
-choanocytes
-mesohyl layer
-amoebocytes
Porifera choanocytes purpose
-flagellated collar cells
-generate a water current through the sponge and ingest suspended food
Porifera mesohyl layer characteristics
gelatinous layer between two cell layers
Porifera amoebocytes purpose
totipotent cells in the mesohyl that play roles in digestion and manufacture of skeletal fibers (spicules)
Porifera reproductive properties
-most are hermaphrodites and exhibit sequential hermaphroditism
Porifera classes
Calcarea, Hexactinellida, Demospongiae
characteristics of Calcarea class in Porifera
typically have calcium carbonate (calcareous) spicules wiht 1, 3, or 4 rays
characteristics of class Hexactinellids in Porifera
glass sponges with 6-rayed siliceous spicules
characteristics of class Demispongiae in Porifera
have siliceous spicules, spongin fibers, or both
Types of Porifera Canal systems
-Asconoids
-Syconoids
-Leuconoids
what are asconoids?
flagellated spongocoels in Porifera
characteristics of asconoids in Porifera
-simplest body form
-small and tube-shaped
-water enters the spongocoel
characteristics of the spongocoel in the asconoid canal system of Porifera
-lined with choanocytes which pull water through; all Calcarea are asconoids
examples of asconoids
Leucosolenia and Clathrina
what are syconoids?
flagellated canals
characteristics of syconoids in Porifera
-resemble asconoids but are larger with a thicker body wall
-wall contains choanocyte-lined radial canals that fold back and forth to make canals that empty into spongocoel
how does water flow in syconoids in Porifera?
enters radial canals through tiny openings called prosopyles, then to radial canals, then apoopyle to spongocoel
what is the spongocoel lined with in syconoids?
epithelial cells
what are leuconoids in Porifera?
flagellated chambers
characteristics of leuconoids
-most complex of canal systems
-most sponges are leuconoid
how does water flow in leuconoids?
clusters of flagellated chambers are filled from incurrent canals and discharge to excurrent canals
Porifera sexual reproduction
-most are monoecious
-sperm sometimes arise from transformed choanocytes
-the free-swimming larvae of sponges is a solid parenchyma
Porifera asexual reproduction
-can occur by bud formation (external buds or internal buds) or fragmentation
external buds
-budding
-small individuals that break off after attaining a certain size
internal buds
-gemmules
-formed by archaeocytes that collect in mesohyl
-coated with tough spongin and spicules
-survive harsh environmental conditions
symmetry
balanced proportions of parts on opposite sides of a median plane
asymmetrical
no plane through which they can be divided into identical halves
radial symmetry
-body divided into similar halves by more than two planes passing through longitudinal axis
-usually sessile, freely floating, or weakly swimming animals
-no anterior or posterior end
primarily radial phyla
Cnidaria and Ctenophora
advantages of radial symmetry
can interact with the environment in all directions
bilateral symmetry
organism can be divided along a sagittal plane into two mirror portions: right and left halves
-associated with cephalization
advantages of bilateral symmetry
much better for directional (forward) motion for animals moving through their environments head first
how do most animals reproduce
sexually
what life stage dominates life cycle typically
diploid stage
when does the sequence of inherited development begin?
after fertilization of an egg to form a zygote
cleavage
rapid cell division
morula
a ball of cells made through cleavage
blastrulation
formulation of a blastula
blastula
multicellular hollow ball of cells that develops into cavities for organs
cleavage patterns
radial and spiral
radial cleavage
the cleavage planes are symmetrical to the polar axis and produce layers of cells on top of each other in an early embryo
spiral cleavage
the process by which cells of the early embryo divide and spiral around the pole-to-pole axis of the embryo
blastocoel
fluid-filled space in a blastula
what does the blastula become in animals other than sponges?
the two layered stage called a gastrula with an endoderm and ectoderm
ectoderm
surrounds blastocoel
endoderm
surrounds and defines an inner body cavity called the gastrocoel
invagination
transition between blastula and gastrula
what does the archenteron develop into
the digestive system of an animal
archenteron
primitive gut in the gastrula
coelom
true body cavity
what are coeloms derived from
mesoderm
coelomates
animals that possess a true coelom
pseudocoelom
body cavity derived from the mesoderm and endoderm
pseudocoelomates
triploblastic animals that possess a pseudocoelom
acoelomates
triploblastic animals that lack a body cavity
functions of a body cavity
-fluid cushions the suspended organs
-fluid acts like a skeleton against which muscles can work
-the cavity enables internal organs to grow and move independent of the outer body wall
coelomate types
schizocoely and enterocoely
schizocoely
mesodermal cells migrate to blastocoel
enterocoely
coelom comes from pouches off the archenteron that push outward into the blastocoel
what do germ layers develop into
tissues and organs of the animal embryo
ectoderm
the germ layer covering the embryo’s surface
endoderm
innermost germ layer; lines the developing digestive tube (archenteron)
mesoderm
middle layer of cells
diploblastic animals
only have ectoderm and endoderm (cnidarians and a few other groups)
triploblastic animals
have ectoderm, mesoderm, and endoderm
types of triploblastic organisms
-deuterostomes
-protostomes
deuterostomes
-blastopore becomes anus
-name means second mouth (mouth forms from second opening in the embryo)
deuterostomes phyla
Echinodermata, Hemichordata, Chordata
protostomes
-name means first mouth (refers to the formation of the mouth from the embryo blastopore)
-anus forms secondarily
first characteristic of phylum Cnidaria
contain specialized cells: cnidocytes
cnidocytes
specialized cells housing nematocysts
nematocysts
stinging organelles
second characteristic of phylum Cnidaria
all are aquatic and mostly marine
third characteristic of phylum Cnidaria
radially symmetric
fourth characteristic of phylum Cnidaria
diploblastic
germ layers of Cnidaria
epidermis, gastrodermis, mesoglea (extracellular nonliving matrix)
fifth characteristic of Cnidaria
no coelomic cavity
sixth characteristic of Cnidaria
two body types
body types of Cnidaria
-free swimming medusa
-polyp form (attached)
seventh characteristic of Cnidaria
incomplete gut (gastrovascular space)
-only one hole
eighth characteristic of Cnidaria
hydrostatic skeleton
ninth characteristic of Cnidaria
nerve net (nervous system)
tenth characteristic of Cnidaria
asexual and sexual reproduction
are Cnidaria carnivores, herbivores, omnivores, or parasites?
carnivores
how do Cnidaria capture prey
tentacles armed with cnidocytes
operculum
covers nematocyst in Cnidaria
cnidocil
trigger structure that cnidocytes are equipped with in Cnidaria
what happens after discharge of a cnidocyte?
another develops
two basic body plans of Cnidaria
polyp and medusa
Cnidaria polyp form
-hydroid form
-adaptation to a sedentary life
-tubular body with mouth directed upward and surrounded by tentacles
-attach to substratum by pedal disc
-reproduce asexually by budding, fission, or pedal laceration
Cnidaria medusa form
-bell-shaped
-mouth directed downward
-tentacles may extend down
Hydrozoa phylum
Cnidaria
Hydrozoa hydra form
-polyp stage dominant
-bottom end has a basal or pedal disc for attachment
-ring of 6-10 hollow tentacles with cnidocytes that encircle mouth
-medusa contain Velum (shelf)
-reproduce sexually and asexually (budding)
-most are dioecious (either male or female)
-eggs and sperm shed externally
what is the dominant stage (class Schyphozoa, phylum Cnidaria)
medusa
anatomy of class Schyphozoa, phylum Cnidaria
-bells composed mostly of mesoglea
-lack shelf-like velum found in hydrozoan medusae
-mouth located beneath the umbrella
-manubrium forms four oval arms
-tentacles, manubrium, and often entire body may have nematocysts
-4 gastric pouches lined with nematocysts connect with the stomach
reproductive characteristics of class Schyphozoa, phylum Cnidaria
-sexes are seperate
-fertilization occurs internally in the gastric pouch of the female
development of class Schyphozoa, phylum Cnidaria
zygote develops into a ciliated planula larva
-attaches and develops into a schyphistoma
-schyphistoma undergoes strobilation
-forms buds called ephyrae that break loose to form jellyfish medusae
general characteristics of class Cubozoa, phylum Cnidaria
-medusa form dominant
-polyp is inconspicuous or unknown
-strong, fast swimmers
-highly venomous
anatomy of class Cubozoa, phylum Cnidaria
-umbrella is square (box-like)
-one or more tentacles extend from each corner
-at base of each tentacle is a pedalium
pedalium
flat blade at the base of each Cubozoa tentacle
feeding habits of class Cubozoa, phylum Cnidaria
-feed mostly on fish in nearshore areas
-highly venomous
class Anthozoa phylum
Cnidaria
class Anthozoa phylum Cnidaria characteristics
-flower animals
-polyp dominant stage; lack medusa stage
-colorful
where do class Anthozoa live
marine
how big is the class Anthozoa gastrovascular cavity?
large
example of class Anthozoa
sea anemones
how do sea anemone polyps compare to hydrozoan polyps?
larger and heavier
where do sea anemones live?
-attach to shells, rocks, timber, etc with pedal discs
-some burrow in mud or sand
sea anemone anatomy
-crown of tentacles surrounds flalt oral disc
-slit-shaped mouth leads to a pharynx
-gastrovascular cavity divided into six pairs of primary septa or mesenteries tissues
-when in danger, water rapidly expelled through pores as the anemone contracts to a smaller size
types of corals
-soft coral
-hard corals
characteristics of corals
-form sybioses with algae
-secrete a hard exoskeleton
phylum of class Ctenophora
Cnidaria
common name of class Ctenophora
ctenophores
where do ctenophores live?
-marine in warm waters
ctenophores anatomy
-8 rows of comb-like plates of cilia used for locomotion
-nearly all free-swimming, few are sessile
-no head
-luminescent
-two tentacles capture planktonic organisms by means of epidermal cells called colloblasts - no nematocysts
what symmetry do ctenophores have?
radial symmetry
are ctenophores diploblastic or triblastic?
diploblastic (endoderm, ectoderm)
phylum Platyhelminthes common name
flatworms
Platyhelminthes size
a millimeter to many meters in length
are Platyhelminthes parasitic?
some free-living, some parasitic
where do Platyhelminthes live?
all habitats in all biomes (topsoil may contain billions per acre)
how are Platyhelminthes flattened?
dorsoventrally flattened (top to bottom)
what is the symmetry of Platyhelminthes?
bilateral
are Platyhelminthes segmented?
no
are Platyhelminthes triploblastic or diploblastic?
triploblastic
what type of body cavity do Platyhelminthes have
they are acoelomates
characteristic of Platyhelminthes nervous system
highly organized
is the Platyhelminthes gut complete or incomplete?
incomplete
do Platyhelminthes demonstrate cephalization?
yes
can Platyhelminthes regenerate?
yes
how do Platyhelminthes reproduce?
asexually through fragmentation, and sexually which involves several parasitic hosts
-monoecious/cross fertilization
what systems do Platyhelminthes lack?
respiratory, circulatory, skeletal
classes of Platyhelminthes
Turbellaria, Trematoda, Cestoda
what phylum is class Turbellaria under?
Platyhelminthes
anatomy of Turbellaria
-ciliated epidermis
-mouth on ventral side of body, in the middle
-parenchyma cells fill spaces in the body
-extend the pharynx to suck up bits of food
what do Turbellaria eat?
they are carnivorous and detect food with chemoreceptors
what phylum is class Trematoda under?
Platyhelminthes
how developed are Trematoda sense organs?
poorly developed
Trematoda anatomy
-suckers for adhesion (no hooks)
-body covered by a non-ciliated tegument
-increased reproductive capacity
Trematoda parasitic activities
final host usually a vertebrate
what class are Schistosoma a part of ?
Trematoda
common name of Schistosoma
blood flukes
what disease do Schistosomas cause?
schistosomiasis
where are Schistosomas common?
Africa, South America, West Indies, the Middle and far East
what phylum are class Cestoda a part of?
Platyhelminthes
anatomy of Cestoda
-long flat bodies with scolex
-held fast with suckers and hooks
-body covered by a non-ciliated tegument
what is the scolex followed by in class Cestoda?
a linear series of reproductive units or proglottids
does class Cestoda have a digestive system?
no, they absorb nutrients directly from the host’s intestine
class Cestoda common name
tapeworms
class Cestoda reproduction
-increased reproductive capacity
-monoecious
-some practice self-fertilization, although the norm is cross-fertilization from one proglottid to another
class Cestoda parasitic activities
usually two or more intermediate hosts in the life cycle
-final host may be vertebrate or invertebrate
Phylum Nematoda common examples
roundworms, hook worms, pinworms, vinegar eels, etc.
where does phylum Nematoda live?
all habitats in all biomes
-topsoil may contain billions per acre
what is Nematoda’s outer body covering made of?
it is a thick, noncellular cuticle, secreted by the underlying epidermis
what kind of skeleton does Nematoda have?
hydrostatic skeleton
what kind of symmetry does phylum Nematoda have?
bilateral symmetry
are nematodes diploblastic or triploblastic?
triploblastic
what kind of body cavity do nematodes have?
pseudocoelomates
which nerve cords do nematodes have?
one dorsal, one ventral
what kind of digestive system do nematodes have?
complete (mouth and anus are seperate)
at kind of muscles do nematodes have?
longitudinal only
reproductive characteristics of nematodes
seperate sexes and internal fertilization
Nematode example
Ascaris lumbricoides
Ascaris lumbricoides characteristics
occurs in up to 25% of people in some areas of the southeastern US
-a female Ascaris may lay 200,000 eggs a day, which pass out in host’s feces
