Lesson 18: Invertebrates Marine Biology

Classification Overview Common Invertebrates Kingdom Animalia Phlyum Porifera Cnidaria Mollusca Arthropoda Echinodermata Spineless creatures Invertebrates are animals that lack a backbone You may know many examples of these creatures that live in the ocean: jellyfish, sponges, corals, crabs Can you think of others? 2

Phylum: Porifera Simple heterotrophs with two cell types: – Collar cells have flagella and draw water into the sponge’s central cavity (diagram right) – Epithelial cells line the sponge’s outer surface Reproduce asexually by budding or sexually by release of sex cells (gametes) into the water Filter feeders: feed by filtering suspended materials out of water Sponges: Phylum Porifera Flagellum 3 Collar cell The yellow tube sponge, purple vase sponge, red encrusting sponge and gray rope sponge Photo: NOAA

Cnidarians include corals, anemones, sea fans, and jellyfish Cnidarian characteristics: – Radial symmetry – they are symmetrical around a single point, like a clock – Two tissue layers separated by a jelly layer (mesoglea) – Nematocysts – structures on their tentacles that have stinging toxins Phylum Cnidaria: The stinging nettles Cnidarian Taxonomy Some Common Classes Kingdom Animalia Phylum Cnidaria Classes Anthozoa – anemones, Corals Scyphozoa – jellyfish Hydrozoa – fire corals, Portuguese Man-of-War This purple striped jellyfish (Pelagia panopyra) has a potent sting Photo: NOAA 4

Some special Cnidarian species profiles Portuguese Man-of-War Class: Hydrozoa Order: Siphonophora These are in a different class than jellyfish, they are colonies – specialized polyps Photo: NOAA Fire coral Class: Hydrozoa Order: Capitata These are in a different class than typical hard corals - you will get a mild burn if you touch them! 5

Phylum Mollusca: Three defining traits Mollusks include oysters, clams, mussels, conchs, snails, sea slugs, squid and octopuses Most mollusks have three traits – Mantle: a muscular bag surrounding the gills and other organs for circulation – A muscular foot for movement – A radula: a rough scraping appendage for feeding or protection Mollusca Taxonomy Some Common Classes Kingdom Animalia Phylum Mollusca Classes Gastropoda – snails, sea slugs Bivalvia – clams, oysters, scallops, mussels Cephalopoda – squid, octopus 6

Some mollusks Octopus Class: Cephalopoda The foot of the octopus is divided into eight arms. Spiny oyster Class: Bivalvia Bivalves have two shells and no typical “head” like other mollusks Photos: NOAA Foot 7

Phylum Athropoda: Superclass/Subphylum Crustacea Arthropods are land and sea “bugs” Crustaceans include shrimps, crabs, lobsters, copepods and barnacles About 1 million species exist Crustacean characteristics: – Two pairs of antennae – Mandibles for chewing – Hard exoskeleton – Jointed legs Crustacean Taxonomy Some Common Classes Kingdom Animalia Phylum Arthropoda Subphylum Crustacea Classes Cirripedia – barnacles Copepoda – copepods Malacostraca – shrimp, lobster, crabs 8

Some common crustaceans Rock lobster Sub-phylum Crustacea Class Malacostraca Order Decapoda Copepod Sub-phylum Class Crustacea Copepoda Order Harpacticoida Photos: NOAA 9

Phylum Echinodermata: The ocean’s stars Include sea stars (starfish), sea urchins, sand dollars and sea cucumbers Most echinoderms have these traits: – Tube feet for motion – Radial symmetry (adults) Symmetry around a single point – A water vascular system that circulates seawater Echinoderm Taxonomy Some Common Classes Kingdom Animalia Phylum Echinodermata Classes Asteroidea – sea stars Ophiuroidea – brittle stars Holothuroidea – sea cucumbers Echinoidea – sea urchins 10

Some Echinoderms Sunflower star Phylum Echinodermata Class Asteroidea Order Forcipulatida Source: NOAA Sea urchin Phylum Class Echinodermata Echinoidea 11

Crustaceans supporting ecosystems Copepods are tiny crustaceans and one of the most abundant forms of multicellular life in the ocean Why do you think they might be important for marine food webs? They are food for many different types of marine life including sea birds, small fish and whales In this way, they are a very important part of marine ecosystems, providing a foundation for marine food webs 12

Some of the life supported by copepods Photos: NOAA CopepodHerring Tuna Shark Whale Auklet 13

Student activity To figure out what types of organisms make up communities like the sample we just saw (and how many of each type there are), scientists use a process called sampling In today’s activity, we will simulate different types of sampling methods to explore the variety of invertebrates in the ocean 14