Marine Invertebrates THE ANIMAL KINGDOM BASIC CHARACTERISTICS OF

Marine Invertebrates

THE ANIMAL KINGDOM BASIC CHARACTERISTICS OF ANIMALS: MULTICELLULAR ORGANISMS 1. 2. CAPABILITY OF LOCOMOTION 3. MUST INJEST FOOD NINE ANIMAL PHYLA INVERTEBRATES: (8 PHYLA) ALL LACK INTERNAL SKELETON, SOME HAVE EXOSKELTON OR SHELL VERTEBRATES (CORDATES): (1 phylum) INTERNAL SKELTON MADE OF BONE/ CARTILAGE

1. PORIFERA: SIMPLEST ANIMALS NO TISSUE LAYERS EXAMPLES: SPONGES

Phylum Porifera: Sponges 1. Non-moving (sessile) animals 2. No nerves or muscles (no tissue differentiation) 3. Mostly marine 4. Filter feeders: Collect food particles from water 5. Most sponges are hermaphrodites. Hermaphrodites function as both male and female in sexual reproduction by producing eggs and sperm. **All other animals have true tissues

Animals probably evolved from colonial, flagellated protists, like this choanoflagellate colony.

2. CNIDARIA HOLLOW BODY HAVE STINGING CELLS TWO BODY FORMS MEDUSA & POLYP EXAMPLES: CORAL, JELLYFISH, SEA ANEMONE

Cnidarians • Polyp and medusa forms of cnidarians. • Radial symmetry with central digestive (gastrovascular) cavity. • One opening in the gastrovascular cavity serves as both mouth and anus. • Carnivores. • Phylum name comes from specialized cells called cnidocytes. • Cnidocytes are stinging cells used for defense and to capture prey.

Purple striped jelly, Pelagia panopyra

Polyps: Sea anemones

Phylum Ctenophora • The Comb jellies • Resemble cnidarian medusas. • Use cilia for locomotion.

3. PLATYHELMINTHES: EXAMPLES: PLANARIA, FLUKE, TAPEWORM UNSEGMENTED WORMS FLAT WORMS

Phylum Platyhelminthes: Flatworms • Sizes range from microscopic up to 20 meters long (tapeworms). • Many are parasites.

Anatomy of a tapeworm

4. NEMATODA UNSEGMENTED WORMS ROUND WORMS EXAMPLES: HOOKWORMS, HEARTWORMS

Phylum Nematoda: Proboscis (ribbon) worms • Up to 30 meters in length • These worms have a hydraulicallyoperated proboscis that is used to capture prey. • Closed circulatory system.

Nemertea – Proboscis worms

Nematodes

5. ANNELIDA SEGMENTED WORMS MOST ADVANCED WORMS EXAMPLES: LEECH, EARTHWORMS

Phylum Annelida: Segmented worms Sizes range from 1 mm to 3 meters in length. Each segment contains a pair of excretory tubes called metanephridia. Annelids are hermaphrodites that cross-fertilize. Three classes: a. Oligochaeta – earthworms b. Polychaeta – mostly marine c. Hirudinea – leeches

The life history of a blood fluke (Schistosoma mansoni).

Phylum Rotifera: Rotifers • Aquatic • Sizes range from 0. 5 to 2 mm • Complete digestive tract

A rotifer

7. MOLLUSCA SOME HAVE SHELL UNSEGMENTED, SOFT BODIES EXAMPLES: SNAIL, SCALLOP

Phylum Mollusca: Mollusks Snails, clams, octopi, squids, oysters There at least 150, 000 known species All mollusks have similar body plans: a. Muscular foot b. Visceral mass with organs c. Mantle that secretes the shell

Bivalvia Shells divided into two parts. Gills are used for feeding and gas exchange. Example: Clams, oysters

Dreissena polymorpha Zebra mussel

Class: Cephalopoda • Marine organisms • have chromatophores- cells that can change color • “Head-foot” • Highly intelligent • Rapid movement; well-developed nervous systems. Example: Octopus, squid, nautilus, Cuttlefish

6. ARTHROPODA SEGMENTED ANIMALS EXOSKELETONS MADE OF CHITIN CLASS CRUSTACEAN - MARINE ORGANISMS EXAMPLES: SHRIMP, LOBSTER, CRAB, BARNACLE

Phylum Arthropoda: Arthropods (crustaceans, spiders, insects) Hard exoskeleton, segmented bodies, jointed appendages Arthropods are the most successful of all animal phyla based on diversity, distribution, and numbers. Nearly one million species identified so far, mostly insects. The exoskeleton, or cuticle, is composed of protein and chitin. Open circulatory systems in which a heart pumps hemolymph through short arteries and into open spaces (sinuses). Aquatic members- gills for gas exchange; terrestrial members- tracheal system of branched tubes leading from surface throughout body.

Class Crustacea E. g. , crabs, lobsters Almost all are aquatic. Ca. 40, 000 species. Includes krill eaten by whales, and daphnia, copepods, & amphipods in Lake Erie, pill bugs, etc.

8. ECHINODERMATA HAVE A DERMAL SKELETON WITH SPINES & PLATES ONLY LIVE IN MARINE ENVIRONMENT EXAMPLES: SEA URCHIN, SEASTAR, BRITTLE STAR

Phylum Echinodermata (Echinoderms) Water vascular systems – network of hydraulic canals used for locomotion, feeding, and gas exchange. It extends into tube feet that are used for locomotion and feeding. Echinoderms appear to be radial, but are bilateral in larval stages. They have spiny bodies.

9. CHORDATA EXAMPLES: FISH, REPTILES, BIRDS, AMPHIBIANS, MAMMALS HAVE INTERNAL SKELETON BACKBONE TO PROTECT SPINAL CORD