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What does it mean for an organism to be an animal? What does it mean for an animal to be an invertebrate?

Eukaryotic, multicellular, with at least a tissue-level organization. Heterotrophs (non-photosynthetic), require oxygen. Most are mobile.

Invertbrates are animals without a backbone.

What are the three categories as it relates to animal body plan symmetry? What do these categories mean and give examples of animals in each of these categories?

Radial- equal parts radiate out from a central point, top and bottom are distinct, but left and right are not. (Cnidarians - jellyfish, corals and hydra)

Bilateral- Organism can be divided into right and left halves that are more or less equal, with a top and a bottom (Fish, sharks, sea turtles)

Asymmetrical- Having no symmetry (sponges)

What are some of the factors which cause sponges to be unique compared to other animals?

Are sessile (attached to a surface). Numerous tiny pores (Ostice) allow water to pass through the body for filter feeding on plankton and organic matter in the water. Asymmetrical body with no tissues or organs.

Compare the functions of the Choanocytes, Pinacocytes, Porocytes and Amebocytes in sponges.

Choanocytes- Collar cells responsible for feeding, water circulation, respiration, excretion, and reproduction

Pinacocytes- Flattened cells that cover exterior of body

Porocytes- cells with a pore to allow water to pass into body

Amebocytes- Spongin + spicules secreted by internal wandering cells

What forms of reproduction are sponges capable of?

Asexual budding - buds break off and grow into new sponge

Sexual reproduction- sperm release into water to be picked up by nearby sponge nad directed to egg.

Hermaphrodites- produce both sperm and egg

Describe the structure and function of cnidocytes and nematocysts.

Cnidocytes - Located in tentacles used to capture prey and defend against predators

Nematocysts- Contained within cnidocytes. Stinging harpoon-like structures.

What forms of reproduction are Cnidarians capable of?

Sexual reproduction

Asexual reproduction - polyps reproduce by budding. Also by fission.

Compare and contrast the major classes of Cnidarians described in the lecture notes.

Anthozoans - Corals, sea anemones, gorgonians. single or colonial polyps without a medusa. Corals secrete calcium carbonate skeleton and build complex coral reefs

Cubomedusae- small medusae with tentacles armed with powerful nematocysts that may cause death in humans.

Syphozoans- Sea jellies. Large medusae with minute sessile polyps.

What are zooxanthellae and how do they relate to anthozoan cnidarians?

Symbiotic dinoflagellates. They live inside the tissues of anthozoan cnidarians. Essential photosynthetic partners which enable them to thrive in nutrient-poor environments.

Compare and contrast Cnidarians and Ctenophores. How are they similar? How are they different? If you were presented with a living specimen, how would you determine which group it belonged to?

Cnidarians - Radial symmetry, mostly marine, Body forms consist of medusae and polyp. both asexual and sexual reproduction. Have cnidocytes stinger for defense.

Ctenophores - Radial symmetry, lack nematocysts. Both asexual and sexual reproduction. Long sticky tentacles to capture prey. 8 rows of cilia.

Determined by presence of cnidocytes or rows of cillary.

Pick and describe one of the bilaterally symmetrical marine worms. Be sure to mention its phylum, diet, environment / oceanic region that it would be found in, and if there are any significant human interactions that this species or group is known for.

Phylum platyhelmithes - Flatworms

Parasitic flukes and tapeworms.

Diet: absorb nutrients directly from their host’s digestive tract, causing harm to the host.

Inhabit marine, freshwater. They infect fish, and aquatic animals

Human interactions include tapeworms transmitted via undercooked meat, causing nutrient deficiencies.

Compare and contrast the classes of molluscs mentioned in the lecture notes.

Gastropod - Largest group of molluscs (snails, sea slugs, etc)

Coiled shell on most species except sea slugs

Contain Radula for grazing seaweeds

Bivalvia - Specialized filter feeders: clams, oysters, scallops, mussels, shipworms.

Compressed body in mantle cavity between two shells or valves.

Expanded, folded gills for respiratio nand filter feeding

Radula absent

Pick and describe a specific species of mollusk. Be sure to mention its name, its two-part scientific name, which class it is in, what its diet is, which marine environment it is a part of and what sort of interactions it has with humans.

Zebra Mussel - Dreissena polymorpha, Class: Bivalvia

Diet: filter feeders, consuming phytoplankton, small zooplankton, and bacteria.

Environment: Temperate freshwater lakes, rivers and ponds

Human interactions: World’s most invasive aquatic species. Increased water clarity, altered food webs and enrichment of lake floors

What are lophophorates, what phyla are included and what features do they share?

A ciliated feeding structure that is often horse-shoe shaped. Marine and freshwater invertebrates.

Phylum Brozoa- form small colonies. Some are encrusting, others form small fan- or tree-shaped colonies, suspension feeders.

Phylum phronida- Worm-like, living in tubes of sand, circular or horseshoe-shaped lophophore

Phylum Brachiopod- Two shells enclosing body, coiled lophophore.

Both sexual and asexual reprodution.

Compare and contrast the classes of echinoderms presented in the lecture notes.

Sea stars Class Asteroidea: Move with tube feet, Central disc in center of body surrounded by 5 arms, internal organs, calcium carbonate plates. Pedicellariae- pincer-like organs

Brittle stars Class Ophiuroidea: central disc surrounded by flexible arms, internal organs restricted to central disc, tube feet without suckers used for small animals, Gastrovascular cavity.

Sea cucumbers Class Holothuroidea: worm-like, 5 rows of tube feet, still radially symmetrical, skin embedded with calcareous spicules, no spines, deposite feeders, Evisceration- expulsion of the internal organs when disturbed; internal organs regen back.

Crinoids (class crinoidea): 5 or more arms that branch out for suspension feeding. Mostly deep water. Sea lilies live attache in deep water, feather stars crawl on the bottom. Some use a mucous net to aid in food capture.

How can an organism be both an invertebrate and a Chordate? What are the two subphyla of invertebrate chordates and how do they compare to each other.

They have features such as:

Notochord- flexible rod for support of nerve cord, dorsal nerve cord, pharyngeal slits and post-anal tail.

Tunicates (Subphylum Urochordata): only larvae have chrodate characteristics, includes the sea squirts or ascidians, sessile filter feeders. Tunic and scalp

Lancelets (Subphylum Cephalochordate): possess all chordate features as an adult, fish-like body except the absence of a backbone. Small, only up to 3 inches long. Filter feeders in shallow, soft sediments. Gills are used to filter food

Pick and describe a specific species of marine arthropod. Be sure to mention its name, its two-part scientific name, which class it is in, what its diet is, which marine environment it is a part of and what sort of interactions it has with humans.

Sea Spiders (Class Pycnogonida) or Whip scorpion.

Diet: Feed on soft-bodied invertebrates such as sea anemones, hydroids, bryozoans and jellies.

Marine environments: they live in seafloor from shallow intertidal zones to the depths of the oceans

No economic or ecological importance to humans. Not venomous. Interest to scientists studying deep-sea ecosystems and arthropod evolution.