Marine Animals of the Epipelagic and Pelagic Zones
Planktonic organisms are large and small as well as plant and animal. There are several varieties of plant and animal within this species, however, the one characteristic that have in common is that they are all drifters. The word plankton comes from the Greek word "planktos" which means drift hence their name, defining their common trait, organisms that drift or swim weakly in the pelagic zone near the surface of the water. Phytoplankton are unable to propel themselves through the water against currents, therefore drift along with the surface currents, their destination determined by the water movement. Although most plankton are microscopic, plankton come in a wide range of sizes, ranging from microscopic bacteria to large jelly fish and seaweed several feet long. However, most plankton are small, microscopic, single-celled organisms less than a quarter inch -6mm across
. Plankton can be grouped into five categories. These classifications are: bacterioplankton, phytoplankton, zooplankton, mereoplankton, and holoplankton. Bacterioplakton are simple cellular bacteria organisms, phytoplankton are photosynthetic plants, zooplankton are animal plankton that feed on phytoplankton, mereoplankton are larval stages of marine zooplankton and holoplankton are zooplankton that remain as zooplankton throughout their life.
These surface creatures play a fundamental role in marine life, pillars of the aquatic ecosystem forming the life sustaining base of the food chain.
Phytoplankton are single celled plant plankton that are able to photosynthesize. Photosynthesis is the process phytoplankton use to make their own food by trapping sunlight and combining water and carbon dioxide with other substances to make carbohydrates (sugar and starch), proteins and fats. Photosynthesis is the ability of a plant to convert light energy and carbon dioxide into food, then oxygen is released as a byproduct of this chemical reaction.
The oxygen produced by photosynthesis of phytoplankton contributes greatly to our oxygen rich atmosphere
producing over half of the world's oxygen. In fact, these tiny ocean plants called phytoplankton contribute 50 to 85 percent of the oxygen in Earth's atmosphere.
Phytoplankton are at the base of the ocean food chain, a primary producer, harvesting energy directly from the Sun and feeding most ocean life along with those that live off them.
The skeletal structures of phytoplankton are diverse with dynamic geometric spirals, cubes, and cylinders whose purpose is to keep the phytoplankton floating in the photic zone (top 30 meters) where the phytoplankton is able to absorb enough sunlight energy to photosynthesize. Their complex shapes have large surface-areas in relation to their body size, with spiny extensions increasing surface area and friction enabling the phytoplankton to float on the surface of the open water. These microscopic plants, phytoplankton, come in a variety of types.
A variety of diatoms and dinoflagellates live in the Long Island Sound. Diatoms have a skeleton made of silica with a box like structure, which is perforated with holes to allow chemicals to enter and leave. Depending on the species, diatom silica skeletons vary widely. The silica that makes up their skeleton is also the major ingredient in sand and glass.
During the summer in the Long Island Sound, diatom abundance declines to 30% of the phytoplankton mass, as other species, such as the dinoflagellates increase.
Zooplanktons are animal plankton that float and drift with the current. Unlike phytoplankton, they are able to swim. The appendages of zooplankton enable them to move within this abundant food zone. Their sizes range from a microscopic one-tenth of a millimeter to four millimeters. Some zooplankton eat phytoplankton and others prey on smaller zooplankton. In addition, zooplankton are able to eat bacteria, algae, and other fine particles in the water by using their appendages as strainers. Zooplankton that are able to propel themselves are able to move vertically, up and down the water column, eating and avoiding predators. Zooplankton are the primary food source for almost all fish larvae. Zooplankton can reproduce rapidly, and populations can increase by about 30 percent a day under favorable conditions. Zooplankton reach maturity quickly and live short, but productive lives. For example, adult females of a zooplankter called
can produce their body mass in eggs every two to three days.
live an average of one month. One kind of zooplankton that lives in the Long Island Sound is called the copepod. They are tiny crustaceans related to shrimp and are an important food source for larger fish. Adult copepods have long, cylindrical or torpedo-shaped bodies with a single eye and a pair of long antenna at the front, five pairs of legs along the middle and a paddle-like tail at the end. They use their legs for swimming. Copepods use small appendages near their mouths to capture food. Copepods lay eggs that hatch into tiny nauplii that have only three pairs of appendages. Nauplii gain legs and change form as they grow.
Ciliates are another species of zooplankton found in the LIS that feed on phytoplankton such as dinoflagellates. Ciliates have hair like structures called cilia that help them to move, eat and breathe. Other zooplankton that live in the Long Island Sound are Comb Jellies, Moon Jellies, and Sea Gooseberry. Jellies are transparent gelatinous creatures that have adapted to survive. Jellies feed on copepods. Although jellies are a poor food source for most sea creatures, turtles consider them a favorite meal.
Crustaceans also prey on jellies.
Some zooplankton, pump heavy positive ions, positive atoms, out of their bodies, which makes them lighter, enabling them to float.
The organic materials from living and dying plankton sink to the bottom and become food for bottom feeders such as lobsters.
Lions Mane Jelly
The Lions Mane jelly is another very common jelly in the waters on the LIS during the summer months. The dark reddish color makes them easy to recognize. Diameters of six to twelve inches are common sizes for these jellies in southern New England. They have many stinging cells, nematocysts, which are mildly toxic.
Moon Jellies are intriguing zooplankton found in the brackish waters of the Long Island Sound. They live in waters with temperatures between 48? -66? F and ranges in size from 2-15 inches. The moon jelly is a carnivore. Its prey is small plankton, larval crab, shrimp and fish eggs. Although they are considered drifters, which move with the current, moon jellies can propel themselves by pulsing their bell. One way moon jellies catch prey is when it becomes entangled in its outer mucous layer, the food is moved along eight canals and is deposited into the stomach. The moon jellyfish doesn't have any respiratory organs, e.g. lungs, trachea or gills. It breathes by diffusing oxygen from the surrounding water through its thin membranes. Well oxygenated water enters the gastrovascular cavity and low oxygenated water is expelled. Adults can live for a year but polyps can live for up to 25 years!
The developmental stages of scyphozoan jellyfish's life cycle:
Larva searches for site
Moon jellies have a most unusual life cycle. A male releases sperm in the water to fertilize the female's eggs, which resemble purple popcorn. After hatching, the larvae attach to a solid surface and develop into polyps. For years, even decades, the polyp can alternate between feeding, budding into more polyps and spreading. At some point, it produces stacked cuplike sections that launch off as young adults. These finally change into the familiar bell-shaped adults we recognize. What a surprisingly complex life cycle for such an ancient organism!
Green Sea Turtles
Green sea turtles have a unique heart shaped shells, the top shell is smooth with shades of grey, yellow, green , brown, and green. The bottom shell is yellowish white. Adult turtles are herbivores. Green sea turtles pass through in the LIS during the summer eating sea grass and algae. The green turtle is the largest of all the hard-shelled turtles growing up to 4 feet and weighing as much as 400 pounds. Baby sea turtles are extremely vulnerable and are food for large fish, and crabs. Sharks also prey on adult sea turtles. Sea turtles have oxygen reserves that allow them to sleep underwater for more than two hours and dive without surfacing for 30 minutes. The green turtles are now endangered from suffocation and strangulation as a result of discarded trash bags, fishing lines, and balloons mistaken for their favorite meal, jellies.
Blue fish are greenish blue in color, with strong bodies and sharp conical teeth. They are very aggressive finned fish and can grow up to twenty pounds and forty inches long. Their prey includes squid, crabs, shad, herring and smaller blue fish and are known to leave partially prey behind. Predators of the blue fish include shark, tuna, striped bass, and humans.
The cownose ray is a pelagic swimmer and benthic feeder, grey on top and white on the bottom serving as camouflage from predators above and below. It has a sharp venomous stinger at the base of its long thin tail, can weigh up to 50 pounds, and can have a wingspan of 45 inches. They have a skeletal frame made up of cartilage like their relatives the shark and skate. Their habitat is the soft sandy bottom of the LIS floor where prey of clams, invertebrates, and oysters are plentiful. The cownose ray is found at depths between 0 to 22 meters. Mature females give birth to usually one pup. Sharks and humans are this ray's main predator. Humans use them as bait and imitation scallops.
The northern lined seahorse is a fascinating creature who's shape inspired the naming of a part of our brain's anatomy because of its similarity in shape, our hippocampus (Latin for sea horse), responsible for the consolidation of memory. They inhabit the shallow waters of the sound among the grasses ranging up to five inches in length. Seahorses prey are shrimp and other zooplankton. Their predators include
crabs, skates and rays. Seahorses have evolved to be masters of camouflage and excellent hunters. They have no teeth, instead a long snout for sucking in food and a tail for an anchor. Other specialized characteristic include, a horse like head, up right stance, independently moving eyes, the ability to grow appendages and change color. Probably one of the most unusual features of this fish is that the male seahorses becomes pregnant after the female deposits her eggs into the male's pouch. The male seahorse then fertilizes the eggs, incubates them for three weeks and then gives birth to their young, miniature half inch perfect duplicates of their parents.
Atlantic salmon has a long body, its top brownish and silvery sides with black spots. When breeding, the salmon's lower jaw looks like an upward hook in breeding males along with their red side areas. The Atlantic salmon spawns in fresh water, but spends most of its life at sea. They can grow up to four and a half feet and weigh up to eighty pounds. It inhabits the coastal waters of the Atlantic and finds its way into the LIS. Its prey is herring, capelin, sand eel and large plankton and is hunted by seals, sharks, pollack, tuna, skates, halibut, cod, striped bass, bluefish and humans.
Sand Tiger Shark
The Sand Tiger Sharks pups practice in vitro cannibalism, one of the most surprising characteristics of marine creatures. This means that when the "pup" are still inside their mother, they consume each other and any unhatched eggs, resulting in just one pup born at a time. A process of "survival of the fittest" in utero! Once born, the sand tiger shark can grow up to eleven feet long and weigh up to 350 pounds. They live in warmer ocean waters including the Long Island Sound. Sand tiger sharks are slow moving sharks, and eat just about anything. Their predators are other sharks and humans.
Sand tiger sharks are colored light brown to grey on top and lighter shading on their undersides, called countershading, which serves to camouflage it from predator. Other unique features of this creature, is that unlike most other sharks, the sand tiger shark's two dorsal fins are about the same size and its teeth are always visible.
Marine Creatures of the Benthic Zone
Sponges and sea anemone are called epifauna because they can attach themselves to the sea floor. These sea creatures are called filter feeders because they are able to strain out food particles as water passes through their bodies. Much of their diet consists of plankton, although anemone can catch small fish. Finger sponges are common in the LIS, an epifauna, providing shelter to young lobsters and crabs.
The LIS is a habitat for the American lobsters. These lobsters are a greenish brown, but can also be red, albino or blue. They have two large front claws. The larger claw is used for grabbing , crushing and fighting while the smaller claw is used for ripping and tearing. They have eight legs that extend from their abdomen and a wide tail that is used as a powerful thruster in a fight, propelling an enemy backwards offering needed escape time for the lobster. Lobsters molt frequently in the first year of their life because it is growing so quickly, but as an adult it slows down to once every six months to two years. Molting contributes to the lobster's remarkable ability to regenerate their limbs as well as voluntarily release a limb if injured or held captive by an enemy. Regeneration can take up to two-years for an adult, but much less for a juvenile. The lobster is a nocturnal creature spending most of the day hiding in the cracks of rocky regions with its antennae protruding, however when no shelter is available, they burrow into the muddy sea floor. Lobsters are territorial and will aggressively fight to defend their shelters. Lobsters are scavengers, feeding at night and combing the bottom of the water for mollusks, fish and other crustaceans. Their predators include shark, cod, wolfish, goosefish and striped bass in addition to people. When a female lobster carries an egg mass attached to her underside, she is called "berried." One brood produces 8,000- 10,000 lobster larvae. After the larvae hatch, they become part of zooplankton community in the water column living near the surface and drift with the current. After about a month the larval lobster looks more like a miniature adult, is ¾ inch long and moves to the bottom to live as a true benthic creature.
The Common Sea Stars grow to approximately five inches in diameter. They live on the sea floor in rock, gravel or sand. They can be found on the between the low tide line to depths of 160 feet. A sea star eats clams, scallops, and oysters. The sea star has an everted stomach which means it is able to extend its stomach outward and puts its into the tissue of their prey to digests it. The predators of a sea star are spider crabs, and sometimes lobsters. Sea Stars have a water vascular system that carries water and food the its extremities. A fascinating feature of the sea star is that it has an eye at the end of each of its five arms that radiate from its center. These arms can also be regenerated when injured or severed. The underside of each arm has tiny tube feet and a stomach / mouth in the center. Sea stars outer skin it hard, tough and spiny colored brownish red or orange.
A horseshoe crab is one of the most primitive ocean creatures, surviving for almost 300 million years. The horseshoe crab is actually not a crab, but an arachnid a class of arthropods that includes the spider. Horseshoe crabs grow up to 24 inches long and 12 inches wide and 3 or 4 pounds. The horseshoe crab has two main eyes, two light sensitive eyes and a mouth on the bottom. It has a hard brown-segmented helmet- like shell that protects it. The pointed tail helps the horseshoe crab to right itself. Horseshoe crab's preys are worms and bivalves as well as other creatures of the sea floor. They come to shore to spawn in May and June. As adults, their predators include shorebirds and humans; however, their crab eggs are an important source of nourishment for migrating shore birds and their larvae is consumed by a variety of fish
The abundance of horseshoe crabs are reflective of the environmental health of the intertidal area for which they spawn.
Most recently, they have become extremely valuable for their blood because it has blood proteins, which are extremely sensitive to bacteria. The blood of the horseshoe crab is extremely unusual, hemocyanins carry the oxygen in their blood, not hemoglobin. Hemocyarin is comprised of two copper molecules, which give the blood its blue color. In addition, important proteins in the horseshoe crab's blood, a result of their primitive immune system's ability to stop bacterial invasion by clotting, have proved extremely significant. Their sensitivity to bacteria which cause clotting in the presence of bacteria has resulted in every implanted biomedical device, drug , and vaccine certified by the FDA being tested using LAL, ( limulus Amebocyte derived from horseshoe crab blood ) for bacterial contamination.
Mollusks are a category of sea creatures characterized by a soft bodied animal covered with a hard protective shell. They include clams, oysters, mussels, oysters , whelks and snails and are abundant in the sound. Mollusks are classified by shell type. "Bi" is Latin for two, thus bivalve means two shelled animals such as clams, mussels, and oysters. "Uni" means one in Latin, thus one shelled animals are called univalves like snails and whelks. The two shells of a bivalve is connected with a hinge. Univalves have one whole shell often carried on the back of the animal. Bivalves feed on algae. Sea slug, nudibranch, squid are mollusks too, but are exceptions to the existing classifications. Due to adaptations, the shell is these creatures are missing or strongly reduced.