Bivalvia & Cephalopoda

1. Bivalvia & Cephalopoda Welcometo the home of Bivalvia and Cephalopoda. My name is Tim Dillavou and these pages are devoted to giving some background information on bivalves and cephalopods. They will also give some more detailed information on a few species I encountered during a marine ecology class at University of Washington-Tacoma during the spring of 2007. Webpage created by Timothy Dillavou on 05-23-2007

2. Bivalvia Kingdom: animalia Phylum: mollusca Class: Bivalvia Characteristics: • Bivalve refers to having a shell with two halves or valves. • All bivalves have rigid shells to provide support for their soft bodies.  • Bivalvia is the only molluscan class characterized by the absence of a radula. • Live: • Marine or freshwater • In or on top of sediment (epifaunal or infaunal) • Life span varies • Size 2mm to over 4 feet (giant clam of the south pacific) Feeding/Respiration: • Most are filter feeders defined by a gill structure • Some are scavengers or predators • consume phytoplankton and other tiny organic matter that flows through their gills.  • gills function both in respiration and in straining out food particles. • mussels can filter 10-15 gallons of water per day. Locomotion: • muscular "foot" used for burrowing, or swimming (razor clams) • some use foot (byssal threads) for attaching to attaching to substrate (blue mussels) Reproduction: • externally when eggs and sperm are released into water • female may spawn millions of eggs in her lifetime.  Senses: • In many bivalves, the mantle margin has a sensory function and often possesses rows of parallel tentacles with tactile and chemosensory cells. In some species, the siphon tips may also possess such tentacles. Tresus nuttalli (pacific gaper) Crassostrea gigas (Japanese oyster)

3. Species Encountered(Bivalves) back

4. Chlamys rubida(Pacific pink scallop) Description:  • prominent ribs on each valve • grows to about 6 -7 cm long. • swim when threatened • many eyes around the outside, which perceive light and direction.  • One side of shell is covered with a symbiotic sponge.  Geographical Range: • Alaska to San Diego, CA; uncommon S of Puget Sound. Depth Range: • low intertidal to 300 m; mainly subtidal Habitat: • rocky or gravel/mud bottoms. Life span: • up to 6 years.  Reproduction: • externally when eggs and sperm are released into water Humans uses: • harvested by recreational & commercial fishermen because highly desirable seafood. Photos by Hannah Julich, May 2007 back

5. Mytilus californianus(California sea mussel) Description: • color: bluish/ black, concentric growth lines • shell to about 8 inches long Geographical range: • Alaska to southern Baja California Depth Range: • mainly in intertidal zone on outer coast Habitat: • Abundant, on surf-exposed rocks and pier pilings in colonies for protection Feeding: • Filter feeder, prefer to eat fine organic material and plankton Life span: • 10-100 years Reproduction: • Male releases sperm into water and enters female when water is siphoned over gills Photo by Dave Cowles, Little Corona del Mar, CA March 2005 Photos by Bonnie Becker 2007 back

6. Cephalopoda Kingdom: animalia Phylum: mollusca Class: cephalopoda Two subclasses: • Coleoidea: squid, cuttlefish, and octopus • Nautiloidea: nautiluses Characteristics: • A funnel derived from the molluscan foot, circumoral arms that are probably derived from the molluscan head, chitinous beaks Habitat: • all marine, In all seas at all depths, Octopuses are solitary living in cracks and crevices but squid have been known to swim in large groups Life span: • 1-3 years (except for nautilus up to 15 yrs) Feeding: • carnivores: crustaceans, fish, gastropod molluscs Respiration: • gills Locomotion: • walk with use of tentacles (octopus), lateral fins to swim (cuttlefish), jet propulsion (squids almost use exclusively) Shell/Skeleton: • Octopus- absent, squid- pen, cuttlefish- cuttlebone, nautilus- external Reproduction: • Coleoidea - lay hundreds to half a million eggs, Octopus-male typically dies after mating and female dies after guarding eggs • Nautiloidea- lays a few eggs each year Senses: • eyes similar to humans (except for nautilus), touch, storage of chemical info for taste and texture Special notes: • change color, texture, and shape, very intelligent back

7. Species Encountered(Cephalopods)

8. Enteroctopusdoflieni(giant Pacific Octopus) Description: • largest species in the world, up to 400 lbs and 25 feet arm span Geographical range: • Pacific ocean • common in Puget Sound Depth Range: • intertidal to 750 m Habitat: • rocky crevices Feeding: • crustaceans, mollusks, fish Life span: • 3-5 years Reproduction: • female lays between 20,000 to 100,000 eggs and tends the eggs until hatched and then dies Human uses: • food, display in aquariums, and for use as bait in other fisheries Picture by Bonnie Becker, 2007 back Picture by Greg Gilbert The Seattle Times, 2003

9. References • The University of Arizona College of Agriculture and Life Sciences website accessed on 03-31-2007 http://tolweb.org/tree/phylogeny.html • State of Washington website accessed on 04-02-2007 http://depts.washington.edu/natmap/mollusks/3bivafile.html • Bermuda Institute of Ocean Sciences website accessed on 04-03-2007 http://www.thecephalopodpage.org/ • Smithsonian National Zoological Park website accessed on 04-03-2007 http://nationalzoo.si.edu/Animals/Invertebrates/Facts/cephalopods/ • State University of New York College at Cortland website accessed on 03-31-2007 http://www.cortland.edu/ • University of Michigan Museum of Zoology website accessed on 04-04-2006 http://animaldiversity.ummz.umich.edu/site/accounts/information/Bivalvia.html • University of Hawaii at Manoa website accessed on 04-04-2007 www.soest.hawaii.edu • American Society of Limnology and Oceanography website accessed on 04-04-2007 www.aslo.org back