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are mostly marine, colonial organisms that attach to substrates and feed only on microscopic food particles that they take in along with water through numerous external pores.
Where Undigested material and water pass out through an opening at the top called an
do not have nervous, digestive, or circulatory systems. Instead, most rely on maintaining a constant flow of water through their bodies to obtain food, oxygen, and remove wastes....
either remain separate and embedded in the wall of the sponge or united in a continuous scaffolding They provide structural support
Large spicules that are visible to the naked eye
Anthozoa (sea anemones, corals)
are marine animals that consist of polyps, bag-shaped structures with their interiors lined with endoderm forming digestive cavities and a ring of tentacles developed from ectoderm...
are all colonial, with calcite corallites joined to form a corallum. Vertical septa are weakly developed but horizontal partitions, or tabulae, may be well-developed.
are solitary, but some are colonial, and they tend to be more complex than the tabulate corals. Many of the solitary rugose corals have horn-‐shaped corallites composed of...
Most of them have an exoskeleton or a shell of some kind secreted by the mantle. They are all free-‐moving and swim, crawl, or burrow.
Anatomy of Mollusca
The body consists of a head (except in the pelecypods), a foot, and a dorsal portion which includes the internal organs and is covered by the mantle. They have well-‐ developed...
Amphineura Pelecypoda Gastropoda Conularida Pteropoda Scaphopoda Cephalopoda
also known as bivalves, are represented by clams, muscles, and oysters, among others. They are nearly all marine.
Anatomy of Pelecypods
They have a calcareous shell of two valves with bilateral symmetry between the valves. Valve growth begins at an initial point, a beak or umbo, and proceeds outward concentrically.
are represented by the snails, single-‐valved mollusks, and include marine, freshwater, and terrestrial forms
Anatomy of a Gastropod
Their mouth contains a radula, a minutely toothed, filelike, chitinous ribbon, which is typically used for scraping or cueng food before the food enters the esophagus. Some gastropods...
The embryonic shell
The shell grows as a gradually widening cone which is wound around an axial pillar
each coil of the gastropod
last coil where the animal lives
are all the other whorl's together
may have straight, loosely coiled, or tightly coiled shells.
have the simplest suture pattern of the ammonoids. numerous undivided lobes and saddles; typically 8 lobes around the conch. This pattern is characteristic of the Paleozoic ammonoids.
have a more complicated suture pattern than the goniatites. lobes have subdivided tips, giving them a saw-‐toothed appearance, and rounded undivided saddles. This suture...
have the most complicated suture pattern of the ammonoids.lobes and saddles are much subdivided (fluted); subdivisions are usually rounded instead of saw-‐toothed. Ammonoids...
are bilaterally symmetric carnivorous marine animals that are nearly all free-‐ swimming.
Anatomy of a Cephalopod
The circulatory, digestive, nervous, and respiratory systems of cephalopods are all very highly developed compared to those of the other Mollusca. They have a defined head with...
were abundant during the Jurassic and Cretaceous. An example of a fossil belemnoid is Belemnitella (Cret.)
: A hood, formed from the inner pair of tentacles, serves the same function as the operculum in gastropods when the animal withdraws into its shell. Chambers are filled with...
or bristleworms, are Planktonic Tomopteris the largest group of annelids and are mostly marine.
used for locomotion and, in many species, act as the worm’s primary respiratory surfaces
fossilized jaws in polichaetes
Anatomy of a Trilobite
have a dorsal exoskeleton that is longitudinally divisible into three regions, an axial lobe flanked by left and right pleural lobes. The exoskeleton is also transversely divisible...
, which includes spiders and scorpions
horseshoe crabs and an extinct group of sea scorpions called the eurypterids
which includes the sea spiders
formed from the inner pair of tentacles, serves the same function as the operculum in gastropods when the animal withdraws into its shell
a calcareous wall surrounding the siphon
The lines formed by the intersection of the septa with the shell
tubular extension of the mantle
coiled right handed gastropod shell
coiled left handed gastropod shell