CM 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 12 13 14 15 16 17 18 19 Common Invertebrates of the Inter0dal Zone This visual guide is intended to aid you in iden1fying shelled organisms and other commonly captured invertebrates while seining or walking on the beaches of Long Island. Crabs and shrimp are in a different guide. This guide does not list all possible species. Always take photographs of all captures, and use a comprehensive field guide when any species iden1fica1on is debatable. www.portaltodiscovery.org/aday inches 0 1 2 3 4 5 6 7 8 9
Northern Rock Barnacle Barnacles look like @ny limestone volcanoes. Found almost everywhere in the inter@dal zone afached to rocks, shells, and ar@ficial structures. When underwater, the mouth of the shell opens, and the shrimp-like barnacle rakes filters through the water to feed on plankton. Figure 1a. Rock Barnacle Balanus balanoides Figure 1b. Rock Barnacle feeding Balanus balanoides Common Slipper Shell A common gastropod on Long Island. Lives secured to any hard objects, including one another. Shell has a plarorm underneath, giving this animal several common names, "boat shell" or "quarterdeck". Figure 2a. Slipper Shell Crepidula fornicata Figure 2b. Slipper Shell Crepidula fornicata
Periwinkle A common gastropod on rocks and docks. These are herbivorous snails, grazing on algal film growing on rocks. Can live for extended periods out of water by closing up their operculum and wai@ng. Figure 3a. Periwinkle LiCorina licorea Figure 3b. Periwinkle LiCorina licorea Mud Snail A super-abundant gastropod in protected bays and estuaries. Shell oxen looks eroded or worn down. Found on both sandy and muddy bofoms. A scavenger and detritus feeder. Figure 4. Mud Snail Nassarius obsoletus Oyster Drill This gastropod has a flared opening to the shell. Gets its name from its feeding strategy. It grinds its way through the base of an oyster or other bivalve and sucks out the flesh inside. Won't tolerate salinity lower than 15%. Figure 5a. Oyster Drill Urosalpinx cinerea Figure 5b. Oyster Drill Urosalpinx cinerea
Figure 6a. Knobbed Whelk Busycon carica Whelks Long Island's largest snails, shells can exceed 17 cm. Two species found here; the knobbed whelk has pronounced bumps on the body whorl and spire, the channeled whelk has a groove around the body whorl and small closely spaced bumps to the spire. Figure 6b. Channeled Whelk Busycon canaliculatum Figure 6c. Knobbed Whelk spire Busycon carica Figure 6d. Channeled Whelk spire Busycon canaliculatum Moon Snail A large gastropod, predator of other snails. The moon snail will drill a neat round hole in the shell of the prey. Can be found in shallow beach flats to deep water. Figure 7a. Moon Snail Luna1a heros Figure 7b. Moon Snail Luna1a heros
Blue Mussel The blue mussel shell is glossy bluish to black, and grows to 10 cm long. Blue mussels live in estuaries and bays. They afach themselves to any structure with tough byssal threads. They can form dense shoals, which in turn provide structure for a host of seaweed, small fish and invertebrates. Figure 8. Blue Mussel My1lus edulis Ribbed Mussel This salt-marsh organism is found half-buried in the banks of inter@dal streams and mud flats. Shell has ribs down the length (blue mussel does not). Shell grows to 10 cm long. Figure 9. Ribbed Mussel Modiolus demissus Bay Scallop A ribbed bivalve that is about as wide as it is long. Has two wings at the base roughly the same size as the other. One of the very few bivalve species that can swim to avoid predators. Live less than 2 years. An annular ring can be seen on larger specimens. Live scallops have dozens of @ny blue eyes. Figure 10a. Bay Scallop Argopecten irradians Figure 10b. Bay Scallop Argopecten irradians
Oyster This bivalve is extremely variable in shape. Shells are thick and unequal. The lower valve is cemented to the hard object the larval oyster afached to. When areas are healthy, can grow in massive beds providing habitat for many organisms. Figure 11a. Oyster Crassostrea virginica Figure 11b. Oyster Crassostrea virginica Jingle Shell A small bivalve with dissimilar shells. Upper shell is variably shaped, shiny and colored white to gold. Lower shell is flat, fragile and has a large hole. Most less than 5 cm. Figure 12. Jingle Shell Anomia simplex Razor Clam This large bivalve is about six @mes longer than it is wide. Lives burrowed in sand and mud, some@mes in colonies. Figure 13. Razor Clam Ensis directus
SoT-shelled Clam The shell of this bivalve is elongated and thin. They live burrowed into mud flats at low @de. They can detect a human approaching, and will spurt out a fountain of water to dig deeper. Also called 'steamer'. Figure 14. SoT-shelled Clam Mya arenaria Quahog Also called 'hard clam'. Shell thick and strong, broadly oval. Inside white with a purple stain. Nicknames of this bivalve are based on size; 'liflenecks' up to about 4 cm, 'cherrystones' to about 5 cm, and 'chowders' when larger than that. Figure 15. Quahog Mercenaria mercenaria Surf Clam Shell moderately strong, sort of triangular. Outside smooth, white. Some@mes covered with an olive to brown coa@ng. Found in sandy areas below the inter@dal zone on ocean beaches. Can get quite large, to 20 cm. Figure 16. Surf Clam Spisula solidissima Astarte A small, triangular bivalve found in sandy ocean habitat. Shell is heavy and thick, almost smooth with a yellowish-brown to black coa@ng. Several very similar species found on Long Island beaches. Grow to about 2 cm. Figure 17. Chestnut Astarte Astarte castanea
Eastern Sea Star This five-armed echinoderm is most oxen called a 'starfish'. Has hundreds of tube feet on the bofom of each arm, which it uses to move about as well as pry open bivalves, its favorite prey. Found low or below the inter@dal zone, in rocky areas or mussel and oyster beds. Figure 18a. Eastern Sea Star Asterias forbesi Figure 18b. Eastern Sea Star, showing tube feet Asterias forbesi Dwarf BriZle Star BriFle stars are widely varied, some@mes burrowing in sediments and eelgrass beds. The dwarf brifle star can occasionally be found in Long Island @depools. Central disc about 5mm wide, arms around 2 to 3 cm long. Figure 19. Dwarf BriZle Star Amphioplus squamata Purple Sea Urchin An echinoderm covered in short, stout spines. S@ff exoskeleton beneath. A grazer of seaweed, occasional scavenger of dead animals. Found below the inter@dal zone in rocky areas. Figure 20a. Purple Sea Urchin Arbacia punctulata Figure 20b. Purple Sea Urchin, exoskeletons Arbacia punctulata
Whelk Egg Case This confusing object is a long chain of egg cases produced by channeled and knobbed whelks. Each pad has mul@ple embryos inside. Figure 21a. Whelk egg case Busycon spp. Figure 21b. Channeled Whelk, producing eggs Busycon caniculatum Moon Snail Collar This is an egg mass made by the moon snail. It is produced by cemen@ng eggs and sand into a curved ribbon. Very fragile. Figure 22. Moon Snail collar Luna1a heros Skate Egg Case This hooked pouch contains a single embryo of one of the species of skates in local waters. When washed ashore, it has oxen already hatched, leaving an empty husk. Several species of skate have very similar egg cases. Some@mes called 'mermaid's purse'. Figure 23. Skate Egg case Family: Rajadae Other Snail Eggs Figure 24. Mud Snail and eggs Nassarius obsoletus Small marine snails lay individual egg cases afached to vegeta@on, shells, or rocks. Several species of snails lay eggs that may look quite similar, so iden@fica@on beyond 'snail eggs' is suspect. Mud snail shown in figure 24.
Eastern Emerald Elysia A dark green, na@ve sea slug. The Elysia feeds on algae, incorpora@ng the chloroplasts into its own body. This enables the slug to gain limited energy from sunlight. Found in seaweed less than a meter deep. Usually 2 to 3cm long, some@mes bigger. Figure 25. Eastern Emerald Elysia Elysia chloro1ca Snail Opercula Snails have a hard protec@ve barrier which guards the opening of the shell called the operculum (plural: opercula). These are some@mes found on the beach seperated from the animal postmortem. Figure 26. Moon Snail operculum Luna1a heros Jellyfish There are quite a few varie@es of jellyfish found in our waters. Most are harmless. Avoid the tentacles of the lion's mane jellyfish. Many jellies aren't even that closely related, but share similar adapta@ons. In fact, the comb jelly isn't a jellyfish at all. Figure 27a. Comb Jelly Mnemiopsis leidyi harmless Figure 27b. Moon Jelly Aurelia aurita harmless Figure 27c. Lion's Mane Jelly Cyanea capillata painful s.ngs