Knobbed Whelk


Trip to the Beach

Station 1: Whelk

Egg case

Whelk on mirror

Whelk- Carnivore or Herbivore?

• The Knobbed Whelk (Busycon carica) is a gastropod, a soft-bodied invetebrate (animal without a backbone) that is protected by a very hard shell. This mollusk is found in shallow waters of the Atlantic Ocean off the east coast of North America from Massachusetts to northern Florida.

The shell: The Knobbed Whelk has a spiral shell with knobs (or spines) along its shoulder. The whelk's mantle, a thin layer of tissue located between the body and the shell, creates the shell. The whelk builds the hard shell from calcium carbonate that it extracts from the seas. The shell is up to 9.5 inches (24 cm) long. The shell is light gray to tan, and often has brown and white streaks. The shell is not living tissue; it grows as the snail adds more material to the outer edge.

Anatomy: The soft body is divided into the head, the visceral mass, and the foot (which is small). The Knobbed Whelk has two pairs of tentacles on the head; it has a light-sensitive eyespot located on each of the larger tentacles. The smaller pair of tentacles is used for the sense of smell and the sense of touch.

Diet: Knobbed Whelks eat clams. They open the clam with their hard shell, and insert their long proboscis. They eat using a radula, a rough tongue-like organ that has thousands of tiny denticles (tooth-like protrusions).

Station 2:Horseshoe Crab

Horseshoe Crabs

• Horseshoe crabs, common along the Eastern coast, have evolved little in the last 250 million years. Still, they have survived because of their hard, curved shells, which have made it difficult for predators to overturn them and expose their soft, vulnerable underbellies. The horseshoe crab has also survived because it can go a year without eating and endure extreme temperatures and salinity. The Delaware Bay region is home to the largest population of the American horseshoe crab (Limulus polyphemus), which is found along the western shores of the Atlantic Ocean from Maine to the Yucatan.

• The Horseshoe Crab isn't really a crab. Related to scorpions, ticks and land spiders, horseshoe crabs have their own classification

(Class Merostomata). Horseshoe crabs do molt

Horseshoe Crab Facts & Figures

• Despite their size and intimidating appearance, horseshoe crabs are not dangerous.

• A horseshoe crab's tail, while menacing, is not a weapon. Instead, the tail is used to plow the crab through the sand and muck, to act as a rudder, and to right the crab when it accidentally tips over.

• The horseshoe crab's central mouth is surrounded by its legs and while harmless, it is advisable to handle a horseshoe crab with care since you could pinch your fingers between the two parts of its shell while holding it.

• Horseshoe crabs feed mostly at night and burrow for worms and mollusks.

They will, however, feed at any time.

• Horseshoe crabs grow by molting and emerge 25 percent larger with each molt. After 16 molts (usually between 9 and 12 years) they will be fully grown adults.

• Horseshoe crab eggs are important food for migratory shore birds that pass over the Delaware Bay during the spring mating season. Fish also eat the juveniles or recent molts.

Station 3: Moon Snail

Station 3: Moon Snail

• Family: Naticidae. These moderately sized shells belong to a family group numbering several hundred species. Exquisitely patterned, these shells can be found around the world. When fully expanded, the live animal is several times larger than its shell. They are so large, many moon snails cannot fit their entire body inside the shell. Moon snails are also known as whale or shark eyes because of the dark spot in the center of the shell. They have huge appetites and eat several times a day.

Moon snails are carnivorous sand dwellers feeding mainly on clams and other snails. They lay their eggs in collars made of sand and mucus. These collars can be commonly found on most beaches. In about six weeks, the eggs will produce and around

100,000 will hatch. Interesting Facts: Moon Snails can bore a hole in the shell of their prey in as fast as three minutes, using their radular teeth. These teeth are attached to tissue that most resembles a cats tongue. So actually, a moon snail is licking through the shell and not biting it.

These ultra close-up pictures show the polyps of a Purple Sea Whip Coral. The Sea Whip Coral is a colony of hundreds of individual animals. Each animal is called a polyp (say "PAH-lip").

Each polyp is white and has 8 tentacles surrounding the mouth. Each polyp is about 1/4 of an inch tall.

Station 4: Sea whips

A gorgonian, also known as sea whip or is an order of colonial cnidarian (coral) found throughout the oceans of the world, especially in the tropics and subtropics. Individual tiny polyps form colonies and may be whip-like, bushy, or even encrusting. They may be brightly colored, often purple, red, or yellow.

They feed on tiny fish and plankton.

Station 5: Barnacles


• Like shrimp and crabs Barnacles are crustaceans that have jointed legs and shells of connected overlapping plates.

Instead of crawling after food, they glue themselves to rocks, ships, pillings, abalones, and maybe even whales and wait for food to wash by. When barnacles are under water or when a wave washes over them, they reach out little feathery barbed legs to strain out plankton and absorb oxygen.

• A barnacle's fertilized eggs hatch into larva, then they leave the parents' shells. They spend their youth swimming. After many molts they settle down to adulthood, held permanently by one of the strongest known natural adhesives. The barnacle's enemies are worms, snails, sea stars, fish like sheephead, and certain shorebirds. Some are parasites inside crabs or in other animals.

Station 6:

Sea Stars

Everted stomach

Rather than bring the food to the stomach, the sea star brings its stomach to the food. Once the prey is captured the jelly-like stomach actually oozes out of the tiny mouth in a process known as eversion.

When the everted stomach is outside of the sea star’s body it is literally turned inside out, exposing the digestive enzymes to the prey and partially digesting the meal outside of the body. The liquified food is then absorbed through the stomach lining and into the body and is transferred to organs in the arms. When it’s all done feeding the stomach muscles contract, pulling it back inside the body again. Anything inedible, such as shell fragments or spines, are ejected back out of the mouth by muscle contractions.

Station 6: Sea Stars

Tube Feet

• Sea stars move by means of the tube feet, which are operated by a hydraulic, or water-vascular, system unique to echinoderms.

Seawater, circulated through the radiating canals of this system, enters and extends the tube feet. Each tube foot can be withdrawn by its attached muscles. The tube feet are equipped with suction cups, and the animal moves in any direction by gripping with some of its tube feet and pulling itself forward. A sea star that is turned upside down can right itself by turning an arm under and walking with the tube feet.

Station 7: Sea Urchin

• Sea urchins are echinoderms just like sea stars, and just like sea stars they have an internal skeleton that is living tissue that grows with them. It is called a “test”. Among the spines, are five paired rows of tiny feet with suctions to assist in capturing prey and holding onto the sea floor. They have tiny stinging structures that are used in defense against predators and for obtaining food. Like all echinoderms, the purple sea urchin has no brain; they are able to perform everyday tasks by sending signals through their system of nerves. They are able to consume their food because of their claw like mouth. The mouth is located on the underside and it has five tooth like plates which point inwards.

Station 8: Sand (2 basic kinds)

Oahu, HI Sand – (Biogenic Sand)

• Hawaiian beach sand is primarily made up of the shells of tiny snails and broken and worn pieces of larger shells and corals. On beaches with intense wave action, the shell pieces are rounded by the energy of the waves. On more protected beaches the sand is coarser and the particles are more defined, you can see the shell shapes.

Navarre Beach Sand: (broken rock)

• Navarre Beach (Fl) sand is white in color because most of the individual crystals present are quartz (clear).

• Old Woman Beach (Canada) sand is from broken granite which contains quarts as well as feldspar (pink), mica (shiny, grey), and hornblende (dark).

Station 9: Coquina and Oysters


• They are filter-feeders, using siphons to eat - one celled algae, plant pieces in the sand, and detritus. Detritus is nonliving particulate organic material. It typically includes the bodies or fragments of dead creatures as well as fecal material. Detritus is typically colonized by communities of microorganisms which act to decompose (or remineralize) the material. Coquina are the favorite food of many sea birds.





















• Oysters are bivalves that grow straight up in the water in the intertidal zone.

They may be submerged part or all of the day. Like other bivalves they are filter feeders and get their food by siphoning seawater through their body.

Oysters are an indicator species, meaning that their presence in the water can be used to gather information on the overall health of the estuary.

Station 10: Cockle shells

• Cockle is the common name for a group of (mostly) small, edible, saltwater clams, marine bivalve (2 shells) molluscs in the family


• Various species of cockles live in sandy sheltered beaches throughout the world.

• The distinctive rounded shells of cockles are symmetrical, and are heart-shaped when viewed from the end

• The mantle has three apertures

(inhalant, exhalant, and pedal) for siphoning water and for the foot to protrude. Cockles typically burrow using the foot, and feed by filtering plankton from the surrounding water.

• Cockles are capable of 'jumping' by bending and straightening the foot.

Station 11: Nautilus

• Nautilus (from Greek ναυτίλος, 'sailor') is the common name of marine creatures of cephalopod family Nautilidae.

• Nautilidae have survived relatively unchanged for millions of years, and are often considered " living fossils .“

Nautiluses typically have more tentacles than other cephalopods, up to ninety.

These tentacles are arranged into two circles and, unlike the tentacles of other cephalopods, they have no suckers , and are retractable.

• To swim, the nautilus draws water into and out of the living chamber which uses jet propulsion . While water is inside the chamber, it extracts salt from it and diffuses it into the blood. The animal adjusts its buoyancy by pumping gas and fluid into or out of the chambers along the siphuncle.

Station 12: Sponge

Sponges are animals of the phylum Porifera

(meaning "pore bearer"). Their bodies consist of jelly-like mesohyl sandwiched between two thin layers of cells . While all animals have unspecialized cells that can transform into specialized cells, sponges are unique in having some specialized cells that can transform into other types, often migrating between the main cell layers and the mesohyl in the process. Sponges do not have nervous , digestive or circulatory systems . Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes, and the shapes of their bodies are adapted to maximize the efficiency of the water flow. All are sessile aquatic animals and, although there are freshwater species, the great majority are marine (salt water) species. Sponges are considered animals because they are multicellular having specialized cells that are dependent upon one another.

Station 13: Shark

• The Atlantic sharpnose shark is a small shark that attains a maximum size of 4 feet. It has a long snout and folds around its mouth. The triangular smooth edged teeth are similar on both the upper and lower jaws. The Atlantic sharpnose shark can be brown, olive-gray or blue-gray turning to white on the underside.

Adults may have some white spots and smaller individuals tend to have black edged dorsal and caudal fins.

• This shark consumes shrimp, molluscs and small fishes.

• Sexual maturity is reached when an individual is approximately

33 inches. The young are nourished within the female and the young hatch inside the mother’s body then emerge. Litters of 4 to

7 pups are born in June in shallow waters or estuaries. The newborns are 9 to 14 inches in length.

• The Atlantic sharpnose shark is common in coastal waters at depths of 42 feet or less during the summer months. During the winter this shark can be found at depths greater than 90 feet.

Atlanta Sharpnose Shark