The giant squid is a species of deep-ocean dwelling squid in the family Architeuthidae. It can grow to a tremendous size, offering an example of abyssal gigantism: recent estimates put the maximum size at around 12–13 m (39–43 ft) for females and 10 m (33 ft) for males, from the posterior fins to the tip of the two long tentacles. The mantle of the giant squid is about 2 m long, and the length of the squid excluding its tentacles rarely exceeds 5 m (16 ft). Claims of specimens measuring 20 m (66 ft) or more have not been scientifically documented.
The whale shark is a slow-moving, filter-feeding carpet shark and the largest known extant fish species. The largest confirmed individual had a length of 18.8 m (61.7 ft). The whale shark holds many records for size in the animal kingdom, most notably being by far the most massive living non-cetacean animal. It is the sole member of the genus Rhincodon and the only extant member of the family Rhincodontidae, which belongs to the subclass Elasmobranchii in the class Chondrichthyes. Before 1984 it was classified as Rhiniodon into Rhinodontidae.
The megamouth shark is a species of deepwater shark. Rarely seen by humans, it measures around 5.2 m (17 ft) long and is the smallest of the three extant filter-feeding sharks alongside the relatively larger whale shark and basking shark. According to Sharkman's World Organization a total of 286 specimens have been observed or caught since its discovery in 1976. Like the other two planktivorous sharks, it swims with its mouth wide open, filtering water for plankton and jellyfish. It is recognizable from its large head with rubbery lips. The megamouth is so unlike any other type of shark that it is usually considered to be the sole extant species in the family Megachasmidae, though some scientists have suggested it may belong in the family Cetorhinidae.
The dwarf sperm whale is a sperm whale that inhabits temperate and tropical oceans worldwide, in particular continental shelves and slopes. It was first described by biologist Richard Owen in 1866, based on illustrations by naturalist Sir Walter Elliot. The species was considered to be synonymous with the pygmy sperm whale from 1878 until 1998. The dwarf sperm whale is a small whale, 2 to 2.7 m and 136 to 272 kg, that has a grey coloration, square head, small jaw, and robust body. Its appearance is very similar to the pygmy sperm whale, distinguished mainly by the position of the dorsal fin on the body–nearer the middle in the dwarf sperm whale and nearer the tail in the other.
A photophore is a glandular organ that appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye, equipped with lenses, shutters, color filters, and reflectors; unlike an eye, however, it is optimized to produce light, not absorb it.
Ancistrocheirus lesueurii, the sharpear enope squid, is the only species in the genus Ancistrocheirus and family Ancistrocheiridae. With a mantle length of 25 cm (9.8 in), this moderately sized squid may be found throughout the tropical and subtropical oceans. They tend to be found at mesopelagic depths.
The cookiecutter shark, also called the cigar shark, is a species of small squaliform shark in the family Dalatiidae. This shark lives in warm, oceanic waters worldwide, particularly near islands, and has been recorded as deep as 3.7 km (2.3 mi). It migrates vertically up to 3 km (1.9 mi) every day, approaching the surface at dusk and descending with the dawn. Reaching only 42–56 cm (16.5–22 in) in length, the cookiecutter shark has a long, cylindrical body with a short, blunt snout, large eyes, two tiny spineless dorsal fins, and a large caudal fin. It is dark brown, with light-emitting photophores covering its underside except for a dark "collar" around its throat and gill slits.
The kitefin shark or seal shark is a species of squaliform shark in the family Dalatiidae, and the type species in its genus. It is found sporadically around the world, usually close to the sea floor at depths of 200–600 m (660–1,970 ft). With a sizable oil-filled liver to maintain neutral buoyancy, this shark is able to cruise slowly through the water while expending little energy. The kitefin shark, the largest luminous vertebrate on record, has a slender body with a very short, blunt snout, large eyes, and thick lips. Its teeth are highly differentiated between the upper and lower jaws, with the upper teeth small and narrow and the lower teeth large, triangular, and serrated. Its typical length is 1.0–1.4 m (3.3–4.6 ft), though examples as long as 5.9 ft (180 cm) have been encountered.
The pocket shark is a species of kitefin shark in the family Dalatiidae. The species is found in deep water off Chile in the southeastern Pacific Ocean. It was the only member of the genus Mollisquama, until another species, M. mississippiensis, was discovered in the Gulf of Mexico. Both species are distinguished from other sharks by two pockets next to the front fins. The pockets are large, measuring about 4% of the shark's body length. Some researchers hypothesize that the pockets may excrete some kind of glowing fluid or pheromones.
Mollisquama is a genus of pocket sharks in the family Dalatiidae. There are two known species each only known from a single specimen; one found off the coast of Chile and the other found in the Gulf of Mexico.
The largetooth cookiecutter shark is a rare species of squaliform shark in the family Dalatiidae, reported from depths of 60–200 m (200–660 ft) at scattered locations in the Atlantic and Pacific Oceans. As its common name suggests, it is similar in appearance to the cookiecutter shark but has much larger lower teeth. This species reaches a maximum known length of 42 cm (17 in). The largetooth cookiecutter shark feeds by gouging out chunks of flesh from larger animals, including bony fishes, sharks, and marine mammals, and is able to take larger bites than I. brasiliensis. Little is known of its life history; it is thought to be a weaker swimmer than I. brasiliensis, and is presumably aplacental viviparous like the rest of its family. This shark is an infrequent bycatch of commercial trawl and longline fisheries, but is not thought to be much threatened by these activities.
The spined pygmy shark is a species of squaliform shark in the family Dalatiidae found widely in all oceans. Growing no larger than roughly 28 cm (11 in), it is one of the smallest sharks alive, with this record beaten by the dwarf lanternshark. This shark has a slender, cigar-shaped body with a sizable conical snout, a long but low second dorsal fin, and an almost symmetrical caudal fin. Its sister species S. aliae and it are the only sharks with a spine on the first dorsal fin and not the second. Spined pygmy sharks are dark brown to black, with numerous bioluminescent organs called photophores on their ventral surface. The shark is believed to use these photophores to match ambient light conditions, which break up its silhouette and help the shark to avoid being seen by predators below.
The green lanternshark is a species of dogfish shark in the family Etmopteridae, found in the western central Atlantic Ocean. This species usually occurs on the upper continental slope below a depth of 350 m (1,150 ft). Reaching 26 cm (10 in) in length, the green lanternshark has a slender body with a long, thin tail and low, conical dermal denticles on its flanks. It is dark brown or gray with ventral black coloration, which contain light-emitting photophores that may serve a cryptic and/or social function. Green lanternsharks are thought to be gregarious and may attack their prey, squid and octopus often larger than themselves, in packs. Reproduction is aplacental viviparous, with females giving birth to litters of one to three young. This relatively common shark is an occasional, valueless bycatch of commercial fisheries; currently it does not appear to be significantly threatened by human activities.
The fringefin lanternshark is a shark of the family Etmopteridae found in the western central Atlantic from Texas to Florida, northern Gulf of Mexico, and Mexico. It is endemic to this area. It is a deep water shark and is found about 220 to 915 meters below the surface, on the upper continental slopes of the Gulf. E. schultzi is a small shark, about 27–30 cm long and feeds on squid. It is also bioluminescent, which counter-illuminates it and helps with intraspecific interaction. Due to its limited range and the difficulty of collecting deep water species, it has not been evaluated by the IUCN Red List, but due to recent oil spills in the Gulf of Mexico, it is likely that fringefin lanternsharks have decreased in population.
Histioteuthis reversa, commonly known as the reverse jewel squid or the elongate jewel squid, is a species of cock-eyed squid, so called because the eyes are dissimilar. It occurs at moderate depths in the Atlantic Ocean and the Mediterranean Sea. It is also known from the Indian Ocean.
The colossal squid is the world’s largest squid species and the world’s largest mollusc. It belongs to the Cranchiidae family, that of the cockatoo squids or glass squids. It is sometimes called the Antarctic cranch squid or giant squid and is believed to be the largest squid species in terms of mass. It is the only recognized member of the genus Mesonychoteuthis and is known from only a small number of specimens. The species is confirmed to reach a mass of at least 495 kilograms (1,091 lb), though the largest specimens—known only from beaks found in sperm whale stomachs—may perhaps weigh as much as 600–700 kilograms (1,300–1,500 lb), making it the largest known invertebrate. Maximum total length has been estimated between 10 metres (33 ft) and 14 metres (46 ft) but the former estimate is more likely. The colossal squid has the largest eyes of any known creature ever to exist, with an estimated diameter of 27–30 cm (11–12 in) to 40 cm (16 in) for the largest collected specimen.
Livyatan is an extinct genus of macroraptorial sperm whale containing one known species: L. melvillei. The genus name was inspired by the biblical sea monster Leviathan, and the species name by Herman Melville, the author of the famous novel Moby-Dick about a white bull sperm whale. Herman Melville often referred to whales as "Leviathans" in his book. It is mainly known from the Pisco Formation of Peru during the Tortonian stage of the Miocene epoch, about 9.9–8.9 million years ago (mya); however, finds of isolated teeth from other locations such as Chile, Argentina, the United States (California), South Africa and Australia imply that either it or a close relative survived into the Pliocene, around 5 mya, and may have had a global presence. It was a member of a group of macroraptorial sperm whales and was probably an apex predator, preying on whales, seals and so forth. Characteristically of raptorial sperm whales, Livyatan had functional, enamel-coated teeth on the upper and lower jaws, as well as several features suitable for hunting large prey.
Squalus clarkae, also known as Genie's dogfish, is a species of shark from the Gulf of Mexico and western Atlantic. It was described in 2018 and named in honor of ichthyologist Eugenie Clark. It was previously believed to be a part of Squalus mitsukurii, but genetic analysis revealed it to be a distinct species. Individuals are usually between 50 centimetres (20 in) and 70 centimetres (28 in) long. This species is known to be longer in length in comparison to the Squalus Mitsukurii. Their first dorsal fin is also structured differently than the other species in the genus Squalus.
David Gruber is an American marine biologist, a Presidential Professor of Biology and Environmental Sciences at Baruch College, City University of New York, and a National Geographic Explorer.
Rice's whale, also known as the Gulf of Mexico whale, is a species of baleen whale endemic to the northern Gulf of Mexico. Initially identified as a subpopulation of the Bryde's whale, genetic and skeletal studies found it to be a distinct species by 2021. In outward appearance, it is virtually identical to the Bryde's whale. Its body is streamlined and sleek, with a uniformly dark charcoal gray dorsal and pale to pinkish underside. A diagnostic feature often used by field scientists to distinguish Rice's whales from whales other than the Bryde's whale is the three prominent ridges that line the top of its head. The species can be distinguished from the Bryde's whale by the shape of the nasal bones, which have wider gaps due to a unique wrapping by the frontal bones, its unique vocal repertoire, and genetic differences.
