COMMON DOLPHINS

(Delphinus delphis)

Common DolphinPhysical Features
  • Length: Adult: 1.7-2.4m; Newborn: 80-90cm
  • Weight: Adult: 70-110kg
  • Colouration: Common Dolphins are gray, black to brownish on their upper side.  They have an hourglass colouration along their side with a yellowish patch extending from the eye to the dorsal fin and pale gray along the tail stock.  They also have dark gray to black pectoral fins, tail flukes and rostrum.  The under belly is white – off white in colour which can be broken by yellowish or gray lines.  A dark gray line extends from the rostrum to the pectoral fins.
  • Geographic variation in the colour patterns and rostrum length occurs.
  • They have between 80-120 teeth on both the upper and lower jaws.
  • The dorsal fin has a pointed tip and concave trailing edge.
  • The dorsal fins of Common Dolphins are used to identify individuals.  Each dorsal fin has a unique shape, arrangement of notches, colour patterns and scars.

Biology & Ecology

  • Common Dolphins feeding on a variety of fish and cephalopod (squid & octopus) species.
  • This dolphin species are commonly found in open ocean waters off the continental shelf in depths of 180m.
  • In the Byron Bay area, these common dolphins are seasonally present.  Most sightings are made during winter and spring, however, they may be occasionally seen during summer.
  • Common Dolphins may be seen in groups numbering between 10 and 2,000 individuals.
  • Common Dolphins may be found throughout temperate and tropical oceans worldwide.

Behaviour & Social Organisation

  • Common Dolphins are very acrobatic species of dolphin.  They are often seen porpoising, leaping, tail slapping and headlunging.
  • They have been observed on numerous occasions feeding with bottlenose dolphins in the Byron Bay area.
  • Common Dolphins will often approach vessels to bowride.

Acoustic Communication

  • Common Dolphins create a wide range of sounds.  Like other species of toothed cetacea, Common Dolphins produce whistles, echolocative clicks and burst pulse emissions.  These sounds are used for communication, navigation, and feeding amongst other purposes.
Common Dolphin backslap

Common Dolphin displaying a backslap behaviour (c) E. Hawkins 2010