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Lesson Outline

Lesson Outline I. Protozoans II. Porifera III. Cnidarians IV. Ctenophores V. Worm Phyla VI. Mollusks VII. Bryzoans VIII. Arthropods IX. Echinoderms X. Chordates Taxonomic Hierarchy The animal kingdom is divided into major groups called phyla .

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Lesson Outline

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  1. Lesson Outline I. Protozoans II. Porifera III. Cnidarians IV. Ctenophores V. Worm Phyla VI. Mollusks VII. Bryzoans VIII. Arthropods IX. Echinoderms X. Chordates

  2. Taxonomic Hierarchy • The animal kingdom is divided into major groups called phyla. Each phylum is divided into smaller groups called classes, and so on down to the smallest groupings called genus and species: Kingdom Phylum Class Order Family Genus Species

  3. Arthropoda Bryozoa Chordata Mollusca Echinodermata Worm Phyla Cnidaria Ctenophora Porifera Protozoa Animal Kingdom Tree

  4. Phylum Protozoa The protozoa (“first animals”) are single-celled animal plankton called zooplankton. Two important marine protozoa are • Foramanifera • Radiolaria

  5. Niches • A niche is an ecological term used to describe the functional role an organism plays in its environment and, in particular, where it lies in the food chain. For example, a foraminiferan is a single celled animal that feeds on diatoms and dinoflagellates in the plankton. The term zooplankton is also used to describe its niche. A zooplankton organism lives in the plankton and consumes other plankton, both plant and animal.

  6. Heterostegina antillarum (Florida Keys) Photo: Reef Indicators Lab, USF Foraminifera Foraminifera are single-celled animals that feed on phytoplankton. Forams have porous shells of calcium carbonate called tests. Spines and cytoplasmic extensions from the test trap small particles of food. Upon death, the tests fall to the ocean floor where they may comprise an important fraction of the sediments that accumulate on the deep sea bottom.

  7. Radiolarian Photo: Paul Hargraves Radiolaria Radiolaria form porous, symmetrical, glass-like shells made of silica. Like forams, radiolarians have spines to ensnare food. They also have pseudopods for capturing prey. They are most abundant in warm equatorial waters. The bottom sediments in these regions are dominated by radiolarian “ooze”.

  8. The fire sponge, Tedania nigrescens Photo: Columbia University DEES Porifera The Porifera are the sponges, or the “pore-bearing” animals. Approximately 5000 species of sponges are known, of which more than 95% are marine. Sponges are benthic animals, found in nearly all marine regions from the intertidal to the deep-sea. Generally, sponges are sessile, though it has been shown that some are able to move slowly (up to 4 mm per day) within aquaria.

  9. Filter Feeders Sponges are benthic filter feeders. Water is drawn in through small pores in the outer walls by the beating of internal, flagellated cells. These cells filter particles from the water as the water is pumped through the internal canals and chambers, then out other larger openings. The flow of water through the sponge is unidirectional, driven by the beating of the flagella of the internal cells.

  10. Cnidaria (Coelenterata) The name Cnidaria comes from the Greek word “cnidos”, which means stinging nettle. The cnidarians include jellyfish, anemones, corals, and hydras. The members of this phylum are characterized by a gelatinous bodies, tentacles, and stinging cells called cnidoblasts.

  11. The Structure of a Cnidoblast. The stinging cells, cnidoblasts, contain small, sometimes toxic darts coiled up in a capsule. When the trigger is touched, the stinging cell releases the coiled, barbed thread, which wraps around or injects a paralyzing toxin into the prey.

  12. Cnidarians There are three major classes within the phylum Cnidaria: • Hydrozoa • Scyphozoa • Anthozoa

  13. Fire coral (Millepora) Photo: Thomas Gibson, FKNMS Class Hydrozoa Many hydrozoans are colonial, existing as large colonies of individual members. The most well-known hydrozoans are the fire-coral and the Portuguese Man-O’War. Fire corals often cover other structures including corals, but they are not a true coral. They are usually tan-colored with whitish tips. Fire coral is a sessile benthic predator that kills its prey with a powerful sting.

  14. Portuguese Man O’War The Portuguese Man O’War is also a colonial form of hydrozoa. The float is a gas-filled member of the colony. Other members hang downward from the lower surface of the float; some of these have stinging cells. These organisms are able to kill sizable fish with their tentacles.

  15. Class Scyphozoa Scyphozoans include most of the jellyfish familiar to beach-goers and divers. Some jellyfish are pelagic, free-swimming forms of the open ocean. Most species are planktonic, and one order, the Stauromedusae, are sessile on the ocean floor.

  16. Jellyfish Jellyfish range in size 12 mm to more than 2 m across. Their life cycle involves an alternation between sessile polyp stage and a free-swimming medusa stage, though the medusa stage, shown here, usually predominates.

  17. Class Anthozoa This class consists of the true corals, the sea fans, and the sea anenomes.

  18. Coral Anthozoans live exclusively as polyps. While they retain their stinging cells and may feed on prey or particulate food, some anthozoans supplement their diet by growing symbiotic algae in their tissues.

  19. Coral Reefs Most hermatypic (reef-building) corals of the tropics have symbiotic algae, called zooxanthellae, living inside their tissues. For this reason, reef-building corals are exclusively shallow-water dwellers; without light they cannot survive (although solitary corals and anemones may inhabit much cooler and deeper waters).

  20. Sea Anemones Sea anemones are soft-bodied anthozoans that usually attach to rocks or coral. They have a central mouth surrounded by tentacles with stinging cells. Anemones are found in coastal areas all over the world, especially in warmer waters.

  21. Phylum Ctenophora • The common name for this group is the “comb jelly”. The species Mnemiopsis leidyi is found in local waters. These are about the size of a fist, and have a jelly-like body. Comb jellies are not jellyfish, and they lack stinging cells. Ctenophores entrap plankton and detritus with a single pair of tentacles out the back of the animal. Their niche is that of a plankton predator.

  22. The Worm Phyla • Three phyla contain most of the prominent marine species of worms. • Platyhelminthes (Flat worms) • Nemertea (Ribbon worms) • Annelida (Polychaete worms) The marine species in these groups are primarily benthic detritus feeders, an important niche at the base of the detritus food chain.

  23. Photo: University of Wisconsin, Lacrosse Class Turbellaria (Platyhelminthyes) • These small, nonparasitic flatworms live in the bottom in sand or mud, beneath rocks and shells, or on seaweed.

  24. Baseodiscus mexicanus, Gulf of California Photo: MEER Nemertea • Commonly called ribbon worms, Nemerteans live in the bottom mud of coastal waters and are food for a variety of fish and invertebrate predators.

  25. Photo: Greg Rouse Photo: Casey Debenhem, NOAA Polychaete Worms (Annelida) • Polychaete worms have many small projections, called “chaetae”, used to move through the bottom sand or mud. These worms are commonly found inhabiting sponges and oyster clumps from local waters.

  26. Phylum Mollusca Among the more than 50,000 mollusks are some of the most familiar invertebrate marine species, such as clams, snails, and the octopus. Most species of mollusks are benthic, but there are a few pelagic forms, like the nautilus and squid.

  27. Physical Characteristics of Mollusks • Three body regions: a head, a visceral mass, and a foot. • An extension of the body wall called the mantle, responsible for secreting the shell. • A radula (tongue like feature) used to rasp away at food. • Well developed body organs (nervous system, circulatory system, respiratory system, etc.), but no body segmentation.

  28. Mollusca Classes There are seven classes of mollusks, five of which contain the predominant marine species: • Placophora • Scaphapoda • Bivalvia (Pelecypoda) • Gastropoda • Cephalopoda

  29. Class Placophora Members of the subclass Polyplacophora (“many plates”) are more commonly called the chitons. Chitons are benthic algae feeders that move slowly along hard surfaces. Chitons have an eight part shell with overlapping plates. Often found in the intertidal zone and on sea walls, a chiton uses its muscular foot to attach itself tightly to surfaces.

  30. Class Scaphopoda The scaphopods, or tusk shells, are a small group of benthic detritus feeders. They are sedentary animals with a slender, tubular shell open at both ends. Scaphopods have a well-developed foot, used for burrowing, located at the large end of the shell.

  31. Class Bivalvia The bivalves (“two shells”) are perhaps the most well known mollusks because they are a source of food for humans. Clams, mussels, oysters and scallops are all bivalves. There are about 15,000 known species of bivalves, about 80% of them marine.

  32. Bivalves • Bivalves are common in coastal waters, but may be found anywhere in the ocean. Most species of bivalves are benthic filter feeders. A few species are very motile, like scallops that can swim quickly by opening and shutting their shells. Others, like the clams, can move slowly through the mud on a muscular foot. Still other bivalves, like oysters and mussels, are sessile. While most bivalves are benthic as adults, they have a planktonic larval stage to allow for them to populate new areas of sea floor.

  33. Class Gastropoda The gastropods (“stomach-foot”) make up about 70% of Molluscan species (around 35,000). Most gastropodshave spiral shells, like the conchs, snails, and whelks. A few species do not have any shell.

  34. Gastropods • The gastropods occupy a wide variety of niches, all benthic. Some gastropods are benthic scavengers; others are predatory. Many have a radula that is used to bore through the shell of a clam or snail to eat the animal inside. Conchs snails are an important source of protein in many tropical island areas of the Caribbean. There are a few cone shells in the central Pacific Ocean that can shoot a poison dart up to a few inches that is lethal to humans.

  35. Sea Hares and Nudibranches • The sea hares and nudibranches are colorful gastropods known as the “slugs of the sea” because they lack shells.

  36. Class Cephalopoda While cephalopods (“head-footed”) look different from the other mollusks, they are similar in internal construction. The most obvious difference between most cephalopods and other mollusks is the apparent lack of a shell. The octopods do not have shells at all; the squid have a small internal shell. Nautiluses are the only cephalopods with an external shell.

  37. Squids • The squids are pelagic predators that range in size from a small local one only a few inches long to the giant squid over 60 feet long! Squids have a streamlined tube shape, with 10 tentacles, two being longer and having “suction cups” on the end. Squids swim normally with a pair of fleshy fins on each side, and can go in either direction, or just “hover” in one place. However, they can escape swiftly with a “jet propulsion” by blasting water out of their mantle cavity through their siphon, even adding ink to confuse a predator.

  38. The Far Side, by Gary Larson

  39. Octopods • The octopus has only eight tentacles. The local species is only several feet long, but the one in the cooler waters of the Pacific Northwest may go up to 10 or 12 feet long. The octopus is a benthic predator, feeding mainly on crabs.

  40. Nautilus • The chambered nautilus is a cephalopod having an external shell.

  41. Phylum Bryozoa The Bryozoa (“moss animals”) are benthic filter feeders, consuming bits of detritus and plankton as the water passes by . Bryozoans form colonies attached to rocks and other hard surfaces, and are often among the first organisms to grow on hard substrate (natural or artificial).

  42. Phylum Arthropoda Arthropods (“joint-foot”) have jointed appendages. This class includes crabs, lobsters, shrimp, barnacles. Arthropods have rigid exoskeletons made of chitin, a type of carbohydrate with nitrogen. Aquatic species often have calcium carbonate in it for extra strength. The skeleton provides protection for the animals, and gives support for the internal attachment of the arthropod’s muscles. Although arthropods grow, their exoskeletons do not grow with them. So they must periodically shed, or “molt” their exoskeletons in favor of a new one. Lost limbs can gradually be regenerated after successive moltings.

  43. Arthropod Classes ClassExample 1. Copepoda: Copepods 2. Euphausiacea: Krill 3. Ostracoda: Ostracods 4. Brachiopoda: Brine shrimp 5. Cirripedia: Barnacles 6. Decopoda: Shrimp, lobster, crabs 7. Xiphosura: Horseshoe crabs 8. Stomatopoda: Mantis shrimp

  44. Class Copepoda Copepods are small crustaceans that are the most important zooplankton. They are found almost everywhere where water is available and they constitute the biggest source of protein in the oceans. Most of the economically important fisheries depend on copepods.

  45. Class Euphausiacea After copepods, Euphausiidsare the second most important zooplankton group in the world oceans. Most are herbivorous, but some are omnivorous feeders. Commonly known as “krill”, they are a major food source for adult fish, seals, whales and birds. Larval and immature fish feed on the smaller juvenile euphausiids. Krill live in the dark, at 100 meters or more by day. Many adults migrate to the surface at night to feed on the phytoplankton.

  46. Class Ostracoda A feature that distinguishes an ostracod from other crustaceans is the carapace that encloses the body. Within the carapace are several pairs of short limbs which enable the animal to scramble around and feed on the floor of the sea.

  47. Class Brachiopoda Commonly referred to as “brine shrimp”. Despite a superficially similar appearance to clams, they are actually completely different in their anatomy. They use a fringe of tentacles known as the lophophore to sweep food particles into their mouths.

  48. Class Cirripedia Barnacles attach themselves upside down on a rock with their feet in the water. Inside the “shell” of a barnacle is a segmented body with six pairs of segmented legs used for filter-feeding from the water.

  49. Class Decopoda More than 8,000 species of crustaceans that include shrimp, lobsters, crayfish, hermit crabs, and crabs. Decapods are arthropods with ten main legs. One or more of the five pair may be modified as claws. The walking legs are associated with a skeletal structure called the carapace, which covers both the head and the thorax.

  50. Class Xiphosura Horseshoe crabs, common in Tampa Bay, have evolved little in the last 250 million years. They have survived because of their hard, curved shell, which makes it difficult for predators to overturn them and expose their soft, vulnerable undersides. The horseshoe crab can go a year without eating and endure extreme temperatures and salinity.

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