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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
Sponges Anatomy
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
microscopic ones
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 used to collect food.
tabulate corals
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.
Rugose corals
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 calcite. Septa inside the corallites are typically arranged in four quadrants, leading to them being known sometimes as Tetracoralla.
Phylum Mollusca
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 circulatory, digestive, excretory, and nervous systems. Respiration is carried out by gills includes seven classes of animals:
Mollusca Classes
 Gastropoda Conularida
 Scaphopoda Cephalopoda
The pelecypods
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 use their radula to bore into other shelled animals, while others, such as cone snails, secrete toxins and use them as poisoned harpoons.
The embryonic shell
The shell grows as a gradually widening cone which is wound around an axial pillar
each coil of the gastropod
body whorl
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 pattern is characteristic of Triassic ammonoids and appears again in the Cretaceous “pseudoceratites.”
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 of this type are the most important species from a biostratigraphical point of view. This suture type is characteristic of Jurassic and Cretaceous ammonoids, but extends back all the way to the Permian.
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 a pair of highly developed eyes. The anterior portion of the foot is modified into arms or tentacles which surround the mouth. The mouth has beaklike jaws with calcified tips, and a radula. Internal or external, straight or coiled, aragonitic shells are secreted by the mantle. The soft parts of Nautilus are contained in the outermost compartment, or living chamber, of a coiled shell. A tubular extension of the mantle, the siphon, connects this chamber with the earlier-­‐formed unoccupied chambers through perforations in the septa, which separate the chambers.
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 gas and are connected by the siphuncle, a calcareous wall surrounding the siphon. The lines formed by the intersection of the septa with the shell are called sutures.
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 into three regions, an anterior cephalon, a middle thorax, and a posterior pygidium.
, 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
posterior end
anterior end
coiled right handed gastropod shell
coiled left handed gastropod shell

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