Life span :They live typically for around 20-30 years.

Statistics :They are about 30-60cm (1-2ft)

Physical :DescriptionRat-tails have large heads and long, tapering tails which makes them look like large tadpoles. They have a blunt snout and chin barbels that help them to feel around on the sea bed for food. The mouth is on the underside of the head.

Distribution :They are found in deep waters, from the Arctic to Antarctic.

Habitat : They are benthic or bottom-dwelling fish found to depths of over 3,000m.

DietRat-tails : Has a varied diet, which includes fish, crustaceans and cephalopods.Some feed on animals swimming above the seabed, others pick their food off the sea floor. Some have hard, pointed snouts which allow them to plough through the sediment in search of worms and other small invertebrates.

Octopus

Cephalopods:

Anatomy:

Moving About:

Diet and Digestion:

Reproduction:

Defending Themselves:

They are the sole member of their family Xiphiidae.

Physiology

The swordfish is named after its sharp beak resembling a sword (Latin gladius), which together with its streamlined physique allows it to cut through the water with great ease and agility. Contrary to belief the “sword” is not used to spear, but instead may be used to slash at its prey in order to injure the prey animal, to make for an easier catch. Mainly the swordfish relies on its great speed, capable of reaching speeds up to 50 mph (80 km/h), and agility in the water to catch its prey. One possible defensive use for the sword-like bill is for protection from its few natural predators. The shortfin mako shark is one of the rare sea creatures big enough and fast enough to chase down and kill an adult swordfish, but they don’t always win. Sometimes in the struggle with a shark a swordfish can kill it by ramming it in the gills or belly.

Like most fish, the females grow larger than the males, with males over 300 lb (135 kg) being rare. Females mature at 4–5 years of age in northwest Pacific while males mature first at about 3 to 4 years. In the North Pacific, batch spawning occurs in water warmer than 24°C from March to July and year round in the equatorial Pacific. Adult swordfish forage includes pelagic fish including small tuna, dorado, barracuda, flying fish, mackerel, forage fish as well as benthic species of hake and rockfish. Squid are important when available. Swordfish are thought to have few predators as adults although juveniles are vulnerable to predation by large pelagic fish.

Swordfish skeleton at the National Museum of Natural History, Washington, DC

While swordfish are cold blooded animals, they have special organs next to their eyes to heat their eyes and also their brain. Temperatures of 10 to 15 °C above the surrounding water temperature have been measured. The heating of the eyes greatly improves the vision, and consequently improves their ability to catch prey. Out of the 25 000+ species of bony fish, only about 22 are known to have the ability to heat selected body parts above the temperature of the surrounding water. These include the swordfish, marlin, and tuna.

Swordfish are not schooling fish. They swim alone or in very loose aggregations, separated by as much as 10 meters from a neighboring swordfish. They are frequently found basking at the surface, airing their first dorsal fin. Boaters report this to be a beautiful sight, as is the powerful jumping for which the species is known. This jumping, also called breaching, is thought by some researchers to be an effort to dislodge pests, such as remora or lampreys. It could also be a way of surface feeding by stunning small fish as they jump out of the water, making the fish more easily captured for food.

Swordfish feed daily, most often at night when they rise to surface and near-surface waters in search of smaller fish. They have been observed moving through schools of fish, thrashing their swords to kill or stun their prey and then quickly turning to consume their catch. In the western North Atlantic, squid is the most popular food item consumed. But fish, such as menhaden, mackerel, bluefish, silver hake, butterfish, and herring also contribute to the swordfish diet.

Swordfish are vigorous, powerful fighters. When hooked or harpooned, they have been known to dive so quickly that they have impaled their swords into the ocean bottom up to their eyes. Although there are no reports of unprovoked attacks on humans, swordfish can be very dangerous when harpooned. They have run their swords through the planking of small boats when hurt.

The adults have few natural enemies, with the exception of large sharks, sperm whales, and orcas. They are easily frightened by small boats, yet paradoxically, large craft are often able to draw very near without scaring them. This makes swordfish easy to harpoon.

The swordfish is often mistaken for other billfish (like marlin), but upon examination their physiology is quite different.

Reproduction

Swordfish have been observed spawning in the Atlantic Ocean, in water less than 250 ft (75 m) deep. Estimates vary considerably, but females may carry from 1 million to 29 million eggs in their gonads. Solitary males and females appear to pair up during the spawning season. Spawning occurs year-round in the Caribbean Sea, Gulf of Mexico, the Florida coast and other warm equatorial waters, while it occurs in the spring and summer in cooler regions. The most recognized spawning site is in the Mediterranean, off the coast of Italy. The height of this well-known spawning season is in July and August, when males are often observed chasing females. The pelagic eggs are buoyant, measuring 1.6–1.8 mm in diameter. Embryonic development occurs during the 2 ½ days following fertilization. As the only member of its family, the swordfish has unique-looking larvae. The pelagic larvae are 4 mm long at hatching and live near the surface. At this stage, the body is only lightly pigmented. The snout is relatively short and the body has many distinct, prickly scales. With growth, the body narrows. By the time the larvae reach half an inch long (12 mm), the bill is notably elongated, but both the upper and lower portions are equal in length. The dorsal fin runs the length of the body. As growth continues, the upper portion of the bill grows proportionately faster than the lower bill, eventually producing the characteristic prolonged upper bill. Specimens up to approximately 9 inches (23 cm) in length have a dorsal fin that extends the entire length of the body. With further growth, the fin develops a single large lobe, followed by a short portion that still reaches to the caudal peduncle. By approximately 20 inches (52 cm), the second dorsal fin has developed, and at approximately 60 inches (150 cm), only the large lobe remains of the first dorsal fin.

Harvest

Swordfish were harvested by a variety of methods at small scale (notably harpoon fishing) until the global expansion of long-line fishing. Longline gear can be targeted to a variety of fish, but bycatch remains a significant problem.

Marinated swordfish

Swordfish is a particularly popular fish for cooking. Since swordfish are large animals, meat is usually sold as steaks, which are often grilled. The color of the flesh varies by diet, with fish caught on the east coast of North America often being rosier.

Swordfish are classified as oily fish.^[3] Many sources including the United States Food and Drug Administration warn about potential toxicity from high levels of methylmercury in swordfish.^[4] The FDA recommends that swordfish should not be eaten. (See mercury in fish for more details.)

The flesh of some swordfish can acquire an orange tint, reportedly from their diet of shrimp or other prey. Such fish are sold as “pumpkin swordfish,” and command a premium over their whitish counterparts. (Information from U.S. vendor “Whole Foods.”)

Conservation status

Swordfish are not listed as an endangered species. ^[5]

In 1998, the United States Natural Resources Defense Council and SeaWeb hired Fenton Communications to conduct an advertising campaign to promote their assertion that the swordfish population was in danger due to its popularity as a restaurant entree. ^[6]

The resulting “Give Swordfish a Break” promotion was wildly successful, with 750 prominent U.S. chefs agreeing to remove North Atlantic swordfish from their menus, and also persuaded many supermarkets and consumers across the country.

The advertising campaign was repeated by the national media in hundreds of print and broadcast stories, as well as extensive regional coverage. It earned the Silver Anvil award from the Public Relations Society of America as well as Time magazine’s award for the top five environmental stories of 1998.

Subsequently, the US National Marine Fisheries Service proposed a swordfish protection plan that incorporated the campaign’s policy suggestions. Then-US President Bill Clinton called for a ban on the sale and import of swordfish and in a landmark decision by the federal government, 132,670 square miles (343,600 km²) of the Atlantic ocean were placed off-limits to fishing as recommended by the sponsors.

In the North Atlantic, the swordfish stock is fully rebuilt, with biomass estimates currently 5% above the target level.^[7] There are no robust stock assessments for swordfish in the northwestern Pacific or South Atlantic, and there is a paucity of data concerning stock status in these regions. These stocks are considered unknown and a moderate conservation concern. The southwestern Pacific stock is a moderate concern due to model uncertainty, increasing catches, and declining CPUEs (catch per unit effort). Overfishing is likely occurring in the Indian Ocean, and fishing mortality exceeds the maximum recommended level in the Mediterranean, thus these stocks are considered of high conservation concern. ^[8]
In 2010, Greenpeace International has added the swordfish to its seafood red list. “The Greenpeace International seafood red list is a list of fish that are commonly sold in supermarkets around the world, and which have a very high risk of being sourced from unsustainable fisheries.”^[9]

The order Testudines includes both extant (living) and extinct species. The earliest known turtles date from 215 million years ago,^[2] making turtles one of the oldest reptile groups and a more ancient group than lizards and snakes. About 300 species are alive today, and some are highly endangered.

Like other reptiles, turtles are ectotherms—varying their internal temperature according to the ambient environment, commonly called cold-blooded. However, leatherback sea turtle have noticeably higher body temperature than surrounding water because of their high metabolic rate.

Like other amniotes (reptiles, dinosaurs, birds, and mammals), they breathe air and do not lay eggs underwater, although many species live in or around water. The largest turtles are aquatic.

To be precise, there are 32 types of oceanic dolphins, 5 species of river dolphins and 6 types of porpoises. Let’s have a look at the different types of dolphins list.

Oceanic Dolphins

White Beaked Dolphin: Attaining growth of up to 3 meters, these dolphins are plump looking dolphins with a blackish or gray hide. Even though they are called white beaked dolphins, they feature gray to dark gray beaks, but have a white belly. These dolphins are quite acrobatic and seen to have a unique ‘rooster tail splash’ while swimming rapidly.

Striped Dolphin: These dolphins can be easily distinguished by the stripes on their skin running from their beak all the way around their eyes and down to their rear sides. Hide color varies from one type of striped dolphin to another and may range from gray to brown and appear slighter darker in shade compared to common dolphins. These dolphins are awesome leapers and jump to heights of up to 7 meters. They sure will entertain you with their spins, flips and upside down leaps.

Black Dolphin: These dolphins are small dolphins growing only up to 1.4 meters. They have darker coloration as compared to the common dolphins and feature white coloration on the throat and belly region. Underwater, this dolphin appear tan brown in color. Moreover, a white spot can be found behind the flipper and a dark line is found running along the body. As compared to the other types of dolphins, not much research has been conducted on these black dolphins.

Heaviside’s Dolphin: These dolphins are not quite popular and are found along the Atlantic coasts of southern Africa. The head of this type of dolphin is slightly less conical as compared to the common types of dolphins and have triangular dorsal fins. Gray coloration envelopes the head and thorax, while the dorsal side is bluish-black in color. This dark coloration makes them difficult to spot at sea. These heaviside’s dolphins bear semblance to killer whales, however, they differ from them in habits and size.

Melon-Headed Dolphin: These dolphins are slightly gray in color with a dark gray face, which is why sometimes it is called the ‘mask’. Their head is round in shape, which is why its called the melon-headed dolphin. However, its head is not as round as the pygmy killer dolphin. Capable of swimming quickly, these dolphins are often seen making short low leaps off the sea surface, splashing lots of water.

The other types of dolphins are as follows:

• Bottlenose dolphin
• Dusky dolphin
• Risso’s dolphin
• Hector’s dolphin
• Long-snouted spinner dolphin
• Peale’s dolphin
• Clymene dolphin
• Long-beaked common dolphin
• Short-beaked common dolphin
• Commerson’s dolphin
• Hourglass dolphin
• Pantropical dolphin
• Frasier’s dolphin
• Irrawaddy dolphin
• Rough-toothed dolphin
• Atlantic spotted dolphin
• Atlantic humpback dolphin
• Atlantic white-sided dolphin
• Pacific white-sided dolphin
• Indo-Pacific humpback dolphin
• Southern right whale dolphin
• Northern right whale dolphin
• Pygmy killer whale
• False killer whale
• Orcas (killer whale)
• Long-finned pilot whale
• Short finned pilot whale

River Dolphins

There are four species of dolphins that dwell in the estuaries and freshwater rivers. The four species are as follows:

• Yangtze or Baiji river dolphin
• Boto or Amazon river dolphin
• Ganges or Indus river dolphin
• La Plata dolphin

Out of these four river dolphin species, the first three types reside in freshwater rivers, while the La plata dolphin dwells in the salt-water estuary. However, scientifically this species is clubbed with the river dolphin variety rather than the oceanic type. Living river dolphins do not bear much semblance to their oceanic cousins. Their beaks are extremely large and may even form one-fifth of the total body length. They have extremely well developed brains and short, broad flippers. Moreover, since they live in muddy waters, they do not need vision, which is why they are almost blind. Read more on interesting facts about bottlenose dolphins.

Porpoises

The final category of dolphins in the types of dolphin list are the porpoises. Though mentioned as a category of dolphins, these species are quite different from common dolphins. They are much smaller and have been referred to as small dolphins by sailors and fishermen. They’ve often been overshadowed as dolphins, which is why they have not been able to emerge independently. Unlike common dolphins, their snouts are short and blunt and are shy mammals which is why we rarely see them. There are six types of porpoises, which are as follows:

• Burmeister’s porpoise
• Finless porpoise
• Harbor porpoise
• Vaquita porpoise
• Spectacled porpoise
• Dall’s porpoise

Read more on:

• Why are Pink Dolphins Endangered
• Dolphin Habitat: Where do Dolphins Live

So, this was the list of different types of dolphins. But what types of dolphins are endangered from this list? The Indo-Pacific hump-back dolphin, the amazon river or pink dolphin, the Indus river dolphin and the Yangtze or Baiji river dolphin are at the risk of becoming extinct. Increasing river traffic, river contamination, destruction of tropical rain forests, dam constructions, etc. have caused these amazing sea inhabitants to reach the verge of extinction. Various volunteer programs and organizations have dedicated themselves to the noble cause of saving these dolphins, however, it is the responsibility of each and every individual to help save these endearing creatures of the sea!

Behavior

Dolphins are often regarded as one of Earth’s most intelligent animals, though it is hard to say just how intelligent. Comparing species’ relative intelligence is complicated by differences in sensory apparatus, response modes, and nature of cognition. Furthermore, the difficulty and expense of experimental work with large aquatic animals has so far prevented some tests and limited sample size and rigor in others. Compared to many other species however, dolphin behavior has been studied extensively, both in captivity and in the wild. See cetacean intelligence for more details.

Social behavior

Dolphins are social, living in pods of up to a dozen individuals. In places with a high abundance of food, pods can merge temporarily, forming a superpod; such groupings may exceed 1,000 dolphins. Individuals communicate using a variety of clicks, whistles and other vocalizations. They make ultrasonic sounds for echolocation. Membership in pods is not rigid; interchange is common. However, dolphins can establish strong social bonds. Dolphins will stay with injured or ill individuals, even helping them to breathe by bringing them to the surface if needed.^[17] This altruism does not appear to be limited to their own species however. The dolphin Moko in New Zealand has been observed guiding a female Pygmy Sperm Whale together with her calf out of shallow water where they had stranded several times.^[18] They have also been seen protecting swimmers from sharks by swimming circles around the swimmers^[19][20] or charging the sharks to make them go away.^[21]

Dolphins also display culture, something long believed to be unique to humans (and possibly other primate species). In May 2005, a discovery in Australia found Indo-Pacific Bottlenose Dolphin (Tursiops aduncus) teaching their young to use tools. They cover their snouts with sponges to protect them while foraging. This knowledge is mostly transferred by mothers to daughters, unlike simian primates, where knowledge is generally passed on to both sexes. Using sponges as mouth protection is a learned behavior.^[22] Another learned behavior was discovered among river dolphins in Brazil, where some male dolphins use weeds and sticks as part of a sexual display.^[23]

Dolphins engage in acts of aggression towards each other. The older a male dolphin is, the more likely his body is to be covered with bite scars. Male dolphins engage in such acts of aggression apparently for the same reasons as humans: disputes between companions and competition for females. Acts of aggression can become so intense that targeted dolphins sometimes go into exile as a result of losing a fight.

Male Bottlenose Dolphins have been known to engage in infanticide. Dolphins have also been known to kill porpoises for reasons which are not fully understood, as porpoises generally do not share the same diet as dolphins and are therefore not competitors for food supplies.^[24]

Reproduction and sexuality

Dolphin copulation happens belly to belly and though many species engage in lengthy foreplay, the actual act is usually brief, but may be repeated several times within a short timespan. The gestation period varies per species; for the small Tucuxi dolphin, this period is around 11 to 12 months, while for the Orca the gestation period is around 17 months. They usually become sexually active at a young age, even before reaching sexual maturity. The age of sexual maturity varies by species and gender.

Dolphins are known to have sex for reasons other than reproduction, sometimes also engaging in homosexual behavior.^[25] Various species sometimes engage in sexual behavior including copulation with other dolphin species.^[25] Sexual encounters may be violent, with male dolphins sometimes showing aggressive behavior towards both females and other males.^[25][26] Occasionally, dolphins behave sexually towards other animals, including humans.^[27]

Feeding

Various methods of feeding exist among and within species, some apparently exclusive to a single population. Fish and squid are the main food, but the False Killer Whale and the Killer Whale also feed on other marine mammals.

One common feeding method is herding, where a pod squeezes a school of fish into a small volume, known as a bait ball. Individual members then take turns plowing through the ball, feeding on the stunned fish. Coralling is a method where dolphins chase fish into shallow water to more easily catch them. In South Carolina, the Atlantic Bottlenose Dolphin takes this further with strand feeding, driving prey onto mud banks for easy access.^[28] In some places, Orcas come to the beach to capture sea lions. Some species also whack fish with their fluke, stunning them and sometimes knocking them out of the water.

Reports of cooperative human-dolphin fishing date back to the ancient Roman author and natural philosopher Pliny the Elder.^[29] A modern human-dolphin partnership currently operates in Laguna, Santa Catarina, Brazil. Here, dolphins drive fish towards fishermen waiting along the shore and signal the men to cast their nets. The dolphins’ reward is the fish that escape the nets.^[30][31]

Vocalizations

Dolphins are capable of making a broad range of sounds using nasal airsacs located just below the blowhole. Roughly three categories of sounds can be identified: frequency modulated whistles, burst-pulsed sounds and clicks. Dolphins communicate with their whistles and burst-pulsed sounds, though the nature and extent of that ability is not known. At least some dolphin species can identify themselves using a signature whistle.^[32] The clicks are directional and are for echolocation, often occurring in a short series called a click train. The click rate increases when approaching an object of interest. Dolphin echolocation clicks are amongst the loudest sounds made by marine animals.^[33]

Jumping and playing

Dolphins occasionally leap above the water surface, sometimes performing acrobatic figures (e.g. the Spinner Dolphin). Scientists are not certain about the purpose(s) of the acrobatics. Possibilities include locating schools of fish by looking at above-water signs like feeding birds, communicating with other dolphins, dislodging parasites or simple amusement.

Play is an important part of dolphin culture. Dolphins play with seaweed and play-fight with other dolphins. At times they harass other local creatures, like seabirds and turtles. Dolphins enjoy riding waves and frequently surf coastal swells and the bow waves of boats, at times “leaping” between the dual bow waves of a moving catamaran. Occasionally, they playfully interact with swimmers.

Sleeping

Generally, dolphins sleep with only one brain hemisphere in slow-wave sleep at a time, thus maintaining enough consciousness to breathe and to watch for possible predators and other threats. Earlier sleep stages can occur simultaneously in both hemispheres.^[34][35][36] In captivity, dolphins seemingly enter a fully asleep state where both eyes are closed and there is no response to mild external stimuli. Respiration is automatic; a tail kick reflex keeps the blowhole above the water if necessary. Anesthetized dolphins initially show a tail kick reflex.^[37] Though a similar state has been observed with wild Sperm Whales, it is not known if dolphins in the wild reach this state.^[38] The Indus river dolphin has a different sleep method from other dolphin species. Living in water with strong currents and potentially dangerous floating debris, it must swim continuously to avoid injury. As a result, this species sleeps in very short bursts which last between 4 and 60 seconds.^[39]

Threats

Natural threats

Except for humans (discussed below), dolphins have few natural enemies. Some species or specific populations have none, making them apex predators. For most smaller species, only a few larger species of shark such as the bull shark, dusky shark, tiger shark and great white shark are a potential risk, especially for calves. Some of the larger dolphin species such as Orcas may also prey on some of the smaller species, but this seems rare. Dolphins also suffer from a wide variety of diseases and parasites.^{[citation needed]}

Human threats

Some dolphin species face an uncertain future, especially some river dolphin species such as the Amazon River Dolphin, and the Ganges and Yangtze River Dolphin, which are critically or seriously endangered. A 2006 survey found no individuals of the Yangtze River Dolphin, which now appears to be functionally extinct.^[40]

Pesticides, heavy metals, plastics, and other industrial and agricultural pollutants that do not disintegrate rapidly in the environment concentrate in predators including dolphin from their prey. Injuries or deaths due to collisions with boats, especially their propellers, are also common.

Various fishing methods, most notably purse seine fishing for tuna and the use of drift and gill nets, unintentionally kill many dolphins.^[41] Accidental by-catch in gill nets and incidental captures in antipredator nets that protect marine fish farms are common and pose a risk for mainly local dolphin populations.^[42][43] In some parts of the world such as Taiji in Japan and the Faroe Islands, dolphins are traditionally considered as food, and killed in harpoon or drive hunts.^[44] Dolphin meat is high in mercury and may thus pose a health danger to humans when consumed.^[45]

Dolphin safe labels attempt to reassure consumers that fish and other marine products have been caught in a dolphin-friendly way.

Loud underwater noises, for example resulting from naval sonar use, live firing exercises or certain offshore construction projects such as wind farms may be harmful to dolphins, increasing stress, damaging hearing and causing decompression sickness by forcing them to surface too quickly to escape the noise.^[46][47

The whale was named after a milky white waxy substance, believed to be sperm, found in its own head. It has the largest brain, found in any animal in the world. They can grow up to 59 feet and weigh around 35 to 45 tons. It feeds on several species, but has a taste for the giant squid, its mortal enemy. Whale hunting is a reality, endangering many of the whale species. There are many organizations working towards the protection of these gigantic mammals, however, they still remain vulnerable after decades of protection. The WWF Cetaceans Action Plan aims to ensure that by 2012, a significant reduction of threats to cetacean populations will be achieved. It would be an empty ocean, without these fascinating mammals!