The sperm whale or cachalot [a] Physeter macrocephalus is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus Physeter and one of three extant species in the sperm whale family , along with the pygmy sperm whale and dwarf sperm whale of the genus Kogia. The sperm whale is a pelagic mammal with a worldwide range, and will migrate seasonally for feeding and breeding. The females cooperate to protect and nurse their young.
The 27-metre-long giant sea monster
Largest Eye in the World, Giant Squid | Smithsonian Ocean
The world's biggest squid species have developed huge eyes to give early warning of approaching sperm whales. Colossal and giant squid both have eyes that can measure 27cm 11in across - much bigger than any fish. Scientists found that huge eyes offer no advantages in the murky ocean depths other than making it easier to spot enormous shapes - such as sperm whales. Writing in Current Biology journal , they say this could explain the equally huge eyes of fossil ichthyosaurs. Lead scientist Dan Nilsson from Lund University in Sweden was present at the unique dissection of a colossal squid performed four years ago in New Zealand. In general, other squid species also have eyes that are smaller in proportion to their body size. The streamlined giant squid various species of Architeuthis and the much chunkier colossal squid Mesonychoteuthis hamiltoni can both grow to more than 10m long, as measured from the tip of the body to the end of their tentacles.
The colossal squid Mesonychoteuthis hamiltoni is part of the family Cranchiidae. This species shares anatomy similar to other members of its family although it is the only member of Cranchiidae to display hooks on its arms and tentacles. The first specimens were discovered and described in The colossal squid shares common features to all squids, such as a mantle for locomotion, one pair of gills, and certain external characteristics like eight arms and two tentacles, a head, and two fins. Particularly, of the family Cranchiidae , the colossal squid is the only squid with hooks, swivelling or three-pointed, equipped on its arms and tentacles.
Giant squid have the largest eye in the animal kingdom. At up to 10 inches in diameter, people often describe it as the size of a dinner plate -- or, in other words, as big as a human head. Here, National Museum of Natural History staffer Katie Velazco goes eye-to-eye with a preserved example from the Smithsonian's collection.