Contrary to popular belief, betta fish can live with other fish as long as only one male betta is in the tank. If two male bettas are housed together, they fight.
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.
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.
Of the 15,000 species of bivalves known as clams, some have life cycles of only one year. Individuals of one species called the ocean quahog, or Arctica islandica, however, are among the oldest living animals on Earth, with one captured specimen measured to be more than 500 years of age.
Angler fish, Pacific Viperfish, Wolfish, Goblin Shark and Sloane's Viperfish are just a few of the terrifying fish lurking in the ocean's depths. Once you move past the point where light reaches, the world's oceans turn into a terrifying place filled with strange creatures.
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.
The biggest animal in the ocean, and possibly the largest animal ever to live on Earth, is the blue whale. The maximum recorded weight for a 98-foot blue whale exceeded 209 tons. Longer whales, up to 110 feet, have been seen but not weighed.
It is impossible to estimate the total dolphin population. There are 42 species of dolphin spanning many different regions. Some species' populations are known but no one has estimated the total for all dolphins.
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.
Electric eels can emit up to 600 volts of electricity. The specific electrical output is approximately 100 volts per foot of eel. An eel's shock is strong enough to electrocute a full-grown horse.
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.
According to Montana Fish, Wildlife & Parks, the average lifespan of crayfish is between two and three years. These crustaceans tend to grow to 3 or 4 inches long in Montana but have been known to grow up to 16 inches long in southern states.
A group of stingrays is called a fever. Stingrays normally travel in groups to hunt but are also known to travel individually and in pairs.
Seashells can often be identified by their shape, size, color and habitat, but since there are at least 100,000 species of mollusks, a printed or online identification guide can help. Seashell identification guides provide photographs for comparison, taxonomic details and clues to help differentiate between similar species.
The biggest recorded lobster ever caught weighed 44 pounds, 6 ounces and was caught in 1977. According to the Guinness Book of World Records, it was taken from the waters off the coast of Nova Scotia, and it measured 3 feet 5 inches from the tip of its largest claw to the end of its tail fan.
As of 2014, there are two remaining species of monk seal in the world: the Hawaiian monk seal and the Mediterranean monk seal, both named for the places where they live. A third species, the Caribbean monk seal, was last sighted in 1952 and is considered extinct. Monk seals are unusual in that, unlike most other seals, they prefer a warmer climate with temperate waters and sandy beaches.
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.
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.
According to National Geographic, a leopard seal can hold its breath for up to 10 minutes. This is due to an adaptation that allows the seal to store an extremely large amount of oxygen within the blood and muscles, about three times as much as humans based on weight.
Sharks are found in every ocean in the world and are sometimes found out of their habitat in rivers and streams. There are around 368 species of sharks in the world.
Dwarf crayfish usually grow to 1.5 to 2 inches in length. In the wild, they are brown or gray with brown or blue tints, but a selectively bred bright-orange variety is popular in the aquarium market. Dwarf crayfish thrive in small tanks by themselves or in large tanks with other fish. They are omnivores and eat a variety of plant and animal life.