Phyla of Animalia
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Porifera
Classes
Body Plan
Cell Types
Important Terms
Cnidaria
Classes
General Characteristics
Important Terms
Ctenophora
Platyhelminthes
General Characteristics
Class Turbellaria
Class Monogenea
Class Trematoda
Class Cestoidea
Important Terms
Mollusca
General Characteristics
Class Gastropoda
Class Bivalvia
Class Cephalopoda
Other Classes of Mollusca
Important Terms
Annelida
General Characteristics
Class Polychaeta
Class Polyplacophora
Chitons or Sea cradles
elongated, dorsoventrally flattened
marine,
on rocky intertidal substrates
head reduced in size
shell consists of 8 dorsal plates
chitons are common inhabitants of hard substrates on shallow marine water.
have a muscular mantle that extends beyond the margins of the shell and foot and covers the broad foot
mantle cavity restricted to the space between the margin of the mantle and the foot
articulations in the shell allow chitons to roll into a ball
a linear series of gills is on the mantle cavity on each side of the foot
cilia on the gills create water currents that enter below the anterior mantle margins and exit posteriorly
the digestive, excretory, and reproductive tracts open near the exhalent area
most feed on algae
chemo-receptors, the subradular organ, extends from the mouth to detect food
extracellular digestion absorption occur in the stomach and wastes move on to the intestine
nerve system is ladder like with 4 anterior nerve cords and numerous transverse nerves.
nerve ring encircles the esophagus
sensory structures include osphradia, which are on the mantle margin, chemo-receptors near the mouth, and statocysts in the foot
dioecious
Taken from: http://www.marlin.ac.uk/images/taxonomy_descriptions/polyplacophora.jpg
Class Scaphopoda
the tooth or tusk shells
body enclosed in a tubular shell that is open at both ends
tentacles used for deposit feeding
no head
marine
more than 3000 species
called tooth shells or tusk shells
burrow in moderate depths
head and foot project from the wider end of the shell
incurrent and excurrent water enters and leaves the mantle cavity through the opening at the apex of the shell
functional gills are absent
gas exchange occurs mantle folds
have a radula and tentacles to feed on for a mini ferans
dioecious
trochophore larvae and veliger are produced
Ex: Dentalium
Taken from: http://www.bumblebee.org/invertebrates/images/Dentalium.jpg
Class Monoplacophora
molluscs with a single undivided arched shells
certain structures
are repeated
foot is broad and flat
marine
dioecious
only fossils found until 1952
Ex: Neopilina
Taken from: http://www.ucmp.berkeley.edu/images/taxa/inverts/monoplac_anat.gif
Class Aplacophora
shell, mantle, and foot lacking
head poorly developed
around 250 species
worm-like
borrowing molluscs
marine
called solenogaters
cylindrical molluscs, crawl on their ventral surface
nervous system is ladder like
reminiscent of flat worm body form
most lack nephridia and radula
feed on microorganisms and detritus
Ex: Neomenia
Caudofoveata:
Subclass
of Aplacophora
worm-like molluscs with a cylindrical shell-less body and scale like calcareous spicules
lack eyes, tentacles, statocyst, crystalline style, foot and nephridia
deep water marine burrower
around 70 species
live in vertical burrows on the sea floor
Ex: Chaetoderma