Dolphins

By Larissa Schelbauer

Essencial Languages. Basic. 12/05/2007.

Source: http://en.wikipedia.org/wiki/Dolphins

Scientific classification

Kingdom: Animally

Phylum: Chordate

Class: Mammalia

Order: Cetacean

Suborder: Odontoceti

Family: Delphinidae and Platanistoidea

Gray, 1821

           Dolphins are aquatic mammals which are closely related to whales and porpoises.

There are almost forty species of dolphin in seventeen genera. They vary in size from 1.2 meters (4 ft) and 40 kilograms (88 lb) (Maui's Dolphin), up to 9.5 m (30 ft) and ten tones (the Orca).

 They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating fish and squid.

 The family Delphinidae is the largest in the Cetacean, and relatively recent: dolphins evolved about ten million years ago, during the Miocene.

 Dolphins are considered to be amongst the most intelligent of animals and their often friendly appearance and seemingly playful attitude have made them popular in human culture.

The name dolphins is from Ancient Greek δελφίς dolphin meaning "with a womb" which can be interpreted as meaning “a fish with a womb“.

The word is used in a few different ways. In this article the dolphin is used to for any member of the families Delphinidae and Platanistoidea (oceanic and river dolphins).

A group of dolphin can be called a “school” or a "pod”.

Dolphins are social living in  pods of up to as dozen individuals. In places with a high abundance of food pods can join temporarily forming an aggregation called a super pod.

Some dolphins teach their children to use tools. The dolphin break sponges of and cover their snouts with them thus protecting their snouts while foraging. The knowledge of how use a tool is mostly transferred from mothers to daughters, unlike simian primates, where the knowledge  is generally passed on to both sexes. The technology to use sponges as mouth protection isn’t genetically inherit but a taught behavior.

Male bottlenose dolphins have been known  to engage in  infanticide. Dolphins have  also been known to kill porpoises for reasons which aren’t fully understood as porpoises generally don’t share the same fish diet as dolphin and are therefore not competitor for food supplies.