Predators of Concern to New England Shellfish Growers
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Oyster Drill Predators … Not! Urosalpinx cinerea Vertebrates Habitat: Intertidal to subtidal Mud Shrimp: The adult shrimp depths of 50’, amongst rocks or Bowdoin College Cownose Ray resemble juvenile lobsters but do eNature.com shells, often on the undersides of Rhinoptera bonascus not eat shellfish structures Habitat: Often observed Typical Prey: Feed primarily on in areas with sandy or soft barnacles and oysters but also bottom prey on other bivalves (mussels, Typical Prey: Known to quahogs, etc.). prey on variety of Mud snail: These snails, also Forensic Clues: Straight, small shellfish, especially hole drilled into the prey’s shell. quahogs called Mud Dog Whelks, are usually Lay small, vase-shaped egg cases. Forensic Clues: Leave 2-3’ found on soft, muddy bottoms and Notes: Though native to our region, oyster drills have been wide feeding depressions are scavengers, not predators accidentally introduced around the world, including west coast U.S. with shell fragments and Europe. Starfish, a.k.a., Sea star Flounder, Drum, Northern Puffer, Tautog Periwinkle: These rounded www www Asterias forbesi and Asterias vulgaris Typical Prey: Feed on all shellfish snails are usually found grazing .theseashore.org .soundwaters.org Habitat: Intertidal to eNature.com Forensic Clues: Do not usually consume algae off hard surfaces and do not subtidal depths of 2,000’, the entire animal; more typically nip at pose a threat to shellfish PREDATORS common on rocks or pilings siphons, but also found on soft reducing bottom growth of Concern to Typical Prey: Feed primarily on barnacles, oysters and other bivalve shellfish New England Forensic Clues: Leave gaped open shells with no signs of forced entry Notes: Starfish force open their prey, insert their stomach into the Shellfish Growers shellfish, and eat them in their shell. Eider Ducks, Gulls, Oyster Catchers Oyster Flatworm Typical Prey: Eiders prey on small shellfish, while gulls gather larger Stylochus ellipticus www shellfish which they open by dropping them on hard surfaces; oyster Habitat: Common amongst .sfu.ca catchers break open shellfish with their beaks. oysters or barnacles; also found Forensic Clues: Waterfowl hunt for shellfish by ‘puddling’: tamping under rocks in shallow water their webbed feet Typical Prey: Feed primarily on on intertidal beds oysters and barnacles and bringing Forensic Clues: Leave gaped open shellfish to the shells with no signs of forced surface. Look for entry small, irregular Notes: This worm slides into the open shell of its prey and eats the depressions. Birds animal in its own shell. Very difficult to detect. also leave droppings. Milky Ribbon Worm Cerebratulus lacteus eNature.com Habitat: Intertidal, typically found Woods Hole Sea Grant under stones or buried in sandy or Woods Hole Oceanographic Institution muddy bottom MS #2, 193 Oyster Pond Rd. Typical Prey: Known to prey on soft- Woods Hole, MA 02543-1525 Ph. (508) 289-2398 shell clams and razor clams; may also www.whoi.edu/seagrant consume quahogs Forensic Clues: Leave gaped, open Cape Cod Cooperative Extension shells with no signs of forced entry, P.O. Box 367 but often leave meat in the shell Barnstable, MA 02630-0367 Notes: This worm injects its tooth-like proboscis into its prey and Ph. (508) 375-6849 digests the animal in its shell. www.capecodextension.org Woods Hole Sea Grant • Cape Cod Cooperative Extension 1234567791011 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 Shellfish Predators CENTIMETERS Spider Crab Horseshoe Crab f you are a shellfish grower, harvester, or Libinia dubia and L. emarginata Limulus polyphemus Invertebrates www resource manager, you are well aware that Habitat: Shallow subtidal to Habitat: Intertidal to subtidal Green Crab .soundwaters.org shellfish predators are more than just a depths of 160’ depths of 75’ Carcinus maenas Typical Prey: Typically eat very Typical Prey: Typically eat very nuisance—they are competition! The Habitat: Intertidal to shallow subtidal, soft bottom and rocky small fouling organisms and small small bivalves, and can be I substrates bivalves. Larger individuals have important predators of very Woods Hole Sea Grant Program and the Cape Cod Typical Prey: Very broad diet, but been observed eating oysters by young soft-shell clams. Cooperative Extension Service have teamed up to preys heavily on shellfish, especially inserting a leg into the open shell. Forensic Clues: Leave provide you with information about common hard clams (quahogs) and soft shell Forensic Clues: Chipped shells distinctive feeding pits clams; while hard clams over 20 mm Notes: Can be extremely abundant shellfish predators. This guide provides predator in shell length are relatively safe names and identification tips—including forensic from most green crabs, even adult Rock Crab Whelk soft shell clams are vulnerable to Cancer irroratus www Busycon carica and Busycon canaliculatum clues that will help you identify the culprit, even green crabs. Habitat: Shallow subtidal to .soundwaters.org Habitat: Lower intertidal to subtidal depths of 60’ if you can’t catch it in the act—and describes Forensic Clues: Typically green crabs chip away at the edges of the over 2,500’ deep, on all Typical Prey: Feed mainly on www shellfish; hard clams are often crushed entirely or broken on one bottom types bivalve shellfish, such as quahogs. .andrewjmartinez.com which predators prey on our local shellfish valve; soft shell clams are often chipped open on both valves or Typical Prey: Very broad Unlike most crabs, can prey on species. It also includes information about crushed entirely. diet, including shellfish adult clams. Notes: Native to Europe, green crabs were first recorded on the U.S. Forensic Clues: Chipped Forensic Clues: Heavy chipping organisms that are often mistaken for predators east coast in the early 1800s edges or crushed shells along a shell edge, often with Notes: Typically juveniles little to no damage to the other but are, in fact, innocent! E.R. Degginger Lady Crab are found closer to shore. shell. Lay distinctive With information about your problem (a.k.a., Calico leafy egg cases. Crab) Notes: Whelks use , Color-Pic, Inc. Asian Shore Crab predator(s), you can begin to find a solution, Ovalipes ocellatus Hemigrapsus sanguineus www the hard part of such as exclusion devices, alternative growing Habitat: Intertidal Habitat: Intertidal to shallow .soundwaters.org their foot to hammer to ~30’, primarily subtidal, most often found amongst away at the edge of techniques, siting and planting techniques, and on sandy bottom rocks or other structures the clam shell, until control measures. If you have any questions Typical Prey: Preys Typical Prey: A voracious omnivore, they break in and heavily on shellfish this crab’s diet consists largely of devour the clam. about the information provided in Predators of Forensic Clues: seaweed. These crabs eat a variety They are often Concern to New England Shellfish Growers, or if Chipped edges or crushed shells of intertidal organisms (mussels, buried at low tide. Notes: These very aggressive swimming crabs do not typically appear barnacles, juvenile crabs, etc.) you would like more information about solutions, in traps. Forensic Clues: Chipped shells Moon Snail contact your local extension agent. Notes: Native to southeast Asia, Euspira heros Blue Crab this crab can be extremely abundant and is displacing green crabs Habitat: Lower intertidal to shallow subtidal, on muddy bottom Callinectes sapidus from some rocky intertidal shores. Typical Prey: Feed mainly on bivalve shellfish, such as quahogs and Habitat: Intertidal to shallow subtidal, soft bottom and rocky soft-shell clams, but can also prey on other gastropods. Like whelks, substrates Mud Crab can prey on adult clams. www Typical Prey: Preys heavily on shellfish, including oysters, hard clams Forensic Clues: www Rhithropanopeus harrisii and various .soundwaters.org .andrewjmartinez.com and soft shell clams Panopeus spp. Beveled hole drilled Forensic Clues: Habitat: Intertidal to subtidal depths of into the prey’s shell, Chipped edges or 20’+, commonly found living in and often near the hinge. crushed shells around rocks, oyster beds, and other Lay distinctive sand Notes: These crabs structures collar egg cases. can swim and are Typical Prey: Typically eat very small Notes: They are often very aggressive. fouling organisms and small bivalves. buried at low tide. They do respond to Can be important predators of young traps and are a clams and oysters. major commercial Forensic Clues: Chipped or crushed shells species in many Notes: These small crabs (approx. 1 in.) have powerful claws and can parts of the country. crush small (to 1/2-inch) hard clams. INCHES 123456789 10 11 12 13 14 15 16 17.