Animals of the Benthic Environment

I. Rocky Shores A. Suproalittoral zone – (spray zone) – must avoid drying out, many have shells. a. Rock lice or sea roaches – scavengers. ↑ to 3 cm. Feed at night on organic debris, hide during the day. Rocky Shore Zones WS’s

b. Limpets – flat conical shell and a muscular foot that clings to rock. Feed on marine algae c. Periwinkles – conical shell feed on marine algae

B. High Tide Zone – protective cover to prevent from drying out 1. Periwinkles – move between here and spray zone

2. Buckshot barnacles – protective covering but filter feed so need to under water for a period of time. Larval form is planktonic. 3. Fucus – algae “rock Weed” – cooler latitude thick cell walls to ↓ water loss during low tide. First to colonize rocky shores. 4. Pelvetia – “Rock Weed” – warmer latitude

C. Middle Tide Zone – salt water continuously bathes this area 1. Acorn & gooseneck barnacles – attach to rocks with long muscular necks.

Gooseneck barnacles Acorn Barnacles

2. Mussels – attach to bare rock, algae or barnacles 3. Carnivorous Snails and Sea Stars – feed upon the mussels

3. Anemones – flat foot disc attaches to rock surface 4. Hermit Crabs – inhabit tide pools 5. Sea Urchins – feed on algae

D. Low Tide Zone – almost always submerged 1. algae – abundant, red, green and brown – provides a canopy which animal life can hide under

2. Shore Crabs – various species, scavengers, help keep shore clean II. Sediment Covered Shore A. Sediment – beaches, salt marshes and mud flats

Beaches Marshes Mudflats

B. Sandy Beaches 1. bivalve mollusks – 2 hinged shells, single foot digs into sediment and pulls mollusk down, siphon extends vertically through sediment for feeding 2. Annelid worms – segmented worms a. Lugworms – u-shaped burrows, walls strengthened with mucus. Deposit feeders, eat sand, digests food, sand is passes out

Mollusk Diversity WS

3. Crustaceans – crabs, lobster, shrimp and barnacles. Segmented bodies, hard exoskeleton and paired joints a. Beach hoppers – feeds on kelp cast up by storm waves or ↑ tides. Active at night. b. Sand crabs – bury bodies in sand, filter food particles from water.

4. Echinoderm a. Sand Stars – move through sediments b. Heart urchins – flattened and elongated, live buried in sand near low-tide line. Eat sand and scrape off organic coating. 5. Meiofauna – live in the spaces between sediment particles

C. Mud Flats 1. Eelgrass, Turtle grass – widely distributed in low-tide zone 2. bivalve mollusks

C. Shallow Offshore Ocean Floor – extends from spring low tide shore line to seaward edge of continental shelf. Mainly sediment covered by rocky exposures may occur locally near shore

1. Rocky Bottoms (sublittoral) a. Micro algae b. Bladder Kelp – highly productive. NA Pacific coast attaches to rocks as deep as 30m. Only large storm waves can break them free. c. Bull kelp – highly productive d. Red and Brown algae

e. Sea Hare – feed on kelp f. Sea Urchins – feed on kelp g. Lobsters - crustaceans 1). Spiny - scavengers 2). True – American Lobster – scavengers, feed on live mollusks, crustaceans and other lobsters.

h. Oysters – bivalve mollusks found in estuaries. Need steady clean flow of plankton filled water. 1). Food for: sea stars, crabs, fish, and snails that bore through shell and rasp away soft tissue.