According to National Geographic, the common octopus preys on crabs, crayfish and molluscs. Bottom-dwelling octopuses feed mainly on polychaete worms, crabs, whelks and clams. Open-ocean octopuses subsist on prawns, fish and other cephalopods. The giant Pacific octopus feeds on shrimp, clams, lobsters and fish, and even larger prey, such as sharks and birds.
Crayfish, which are freshwater crustaceans closely related to lobsters, have large claws with which they threaten predators and protect themselves. In addition, when crayfish are frightened, they make menacing gestures with their claws, propel themselves backwards and use their tails to throw mud at their enemies.
According to Discovery of Sound in the Sea, animals use sound to communicate underwater. They emit different types of sounds and gather information on their surroundings by the echoes from those sounds, a process called echolocation.
Oysters are most often found along the Atlantic Coasts and the Gulf of Mexico in North America. They live in estuaries, bays, tidal creeks and even in sounds. Oysters can survive in brackish- to full-strength seawater.
Coral is a colorless marine animal that lives on the ocean floor and can be red, orange and other colors. Any color that appears to be present on coral is a buildup of algae that live on the coral. Like other animals of the sea, coral can change color with emotion.
Sea cucumbers expel their internal organs through their anus to distract and ward off predators. They also evacuate their organs on a seasonal basis, regenerating them afterwards. In addition, some sea cucumbers have special, sticky tubules, part of their respiratory system, which they spew at predators.
A baby blue whale gains about 200 pounds during its first day after birth. In fact, the young whale maintains this daily weight gain throughout its entire first year of life by feeding exclusively on its mother's milk. Each day the newborn also grows about one inch longer.
Among the adaptations of dolphins are hydrodynamic bodies, blowholes on top of their heads, flippers and flukes and echolocation. Some scientists believe that dolphins are able to enjoy the benefits of sleep even while they're in the water by having one half of their brains alert and the other shut down.
The flesh of the barracuda sometimes carries the toxin ciguatera, although it is regularly eaten by humans. Symptoms of ciguatera poisoning include nausea, vomiting and diarrhea. Neurological symptoms, such as headaches, paresthesia and vertigo, often follow. Scarce treatment options exist for ciguatera poisoning, although recovery is possible in time.
When you put a seashell to your ear you are not hearing the ocean, you are hearing the ambient noise coming from inside your ear and around you. The seashell captures and amplifies the noise, which resonates inside the shell and sounds like the rolling waves of the ocean. This effect is called seashell resonance.
Starfish color varies depending on the species and even the presence or absence of environmental threats — most species have the ability to change color, via camouflage, to match their surroundings. Some starfish are naturally tan and dark brown, while others may be light pink or crimson red.
Lobsters breathe through gills, which are located in a structure called the carapace. The carapace is situated at the top of the cephalothorax, which is commonly referred to as the lobster’s head. There are 20 pairs of gills that are separated into two branchial chambers inside the carapace. The gills are made up of short, fine filaments that absorb oxygen directly from the water.
Catfish have a wide variety of predators, including snakes, raccoons, mink, otters, wading birds, alligators, crocodiles, large lizards, humans and other fish. As with most species, catfish have more predators when they are young than when they reach maturity. Some old, large catfish may effectively outgrow all of their predators except humans.
A group of whales is usually called a pod, but other terms for a group of whales include a gam, a herd or a school. A pod usually includes whales that are either related to each other or whales that have formed friendships with each other. Pods are made up of anywhere from two to 30 whales or more.
Most sea sponges are detrivorous, meaning they consume organic debris and various microbes that drift through ocean currents. Harp sponges, however, are carnivorous and use hooks located on their arms to catch shrimp and other small animals.
Sea stars eat either by turning their stomachs inside out and releasing digestive enzymes onto prey or by catching drifting food items and moving them down to their mouths. Sea stars are slow-moving animals, so any prey must be similarly slow-moving or even unmoving. Many sea stars specialize in feeding on slow-moving or sessile bivalves such as clams and mussels or even on other sea stars.
Coastal bottlenose dolphins prefer bottom-dwelling fish and invertebrates, while offshore dolphins eat a variety of fish and squid. More ingenious feeders have been known to trail fishing boats, in the hopes of snagging some leftovers.
Found in Arctic waters, the narwhal is related to the bottlenose dolphin, beluga, porpoise and orca. It is easily distinguishable by the sword-like spiralling tusk that grows through the upper lip of the male. The male's tusk can grow up to 8.8 feet in length although the female grows a much smaller tusk. The narwhal grows anywhere between 13 to 20 feet and weighs up to 3500 pounds.
Cnidarians have groups of similar cells that work together as tissues, while sponges have no tissues, only disconnected regions of specialized cells. Each group has a type of cell unique to their group: Sponges have collar cells, and cnidarians have nematocysts. No sponges are capable of movement as adults, while some cnidarians move as adults.
Seahorses feed on small crustaceans. Some of the favorites for seashores are shrimp and zooplankton, though they will eat nearly any live food.
Both lobsters and cockroaches are arthropods, making them distant relatives. An arthropod is a member of the phylum Arthropoda, which includes insects, crustaceans and arachnids. Arthropods are characterized by a jointed exoskeleton composed of chitin, a segmented body and jointed appendages.
There are several species of eels, which fall into the families of either freshwater or saltwater eels. The two eel families are the family Anguillidae and the family Moninguidae. Eels in the first family share a common genus and reside primarily in North America; those in the latter class generally live in tropical locales and have different body shapes.