Species most likely to be encountered.
Orca or killer whale (Orcinus orca)
A coastal or pelagic species measuring up to 9.8 metres in length, white ventrally with characteristic white markings on the sides, throat, chin and eye, on a black background, tall straight (in males) or curved (in females and juveniles) dorsal fin and no ‘beak’. This species is widely distributed on the Atlantic seaboard, being mainly seen off northern Scotland, and occasionally off the Atlantic coasts of Britain and Ireland in the summer months. Orca have a gestation period of 16 to 17 months, calves are born at any time of the year, measuring 2.0 to 2.5 metres, and are around 4 metres in length when weaned. The species lives in stable groups of 3 to 50, and feeds on squid, fish and marine mammals.
Cuvier's Beaked Whale (Ziphius cavirostris):
A pelagic species measuring up to 7 metres long and living up to 60 years. Body colour varies from tan, pale brown to blue-grey or purplish-black in young animals. Older males are almost white in front of the dorsal fin and have two small teeth (often with barnacles on them) at the tip of the mouth that leave linear scars on other battling males. Females do not have teeth or numerous linear scars, but may show small circular cookie-cutter shark scars. Cuvier’s heads become creamy-white with age and have a distinct ‘squashed’ shape with the lower jaw protruding forward of the upper jaw like a goose-beak. The small dorsal fin is in the last third of the body. All beaked whales lack the median notch between the left and right tail fluke. They suck their prey, primarily deep sea squid, into their mouths so two ventral grooves beneath their chin to help this. Calves are born dark at 2-3 metres long, reaching sexual maturity at 7-11 years old and 5.5-6.1 metres long.
Northern bottlenose whale (Hyperoodon ampullatus)
A pelagic species measuring up to 9.8 metres in length, black dorsally, paler ventrally, with a short ‘beak’ and bulbous head. This species is found in the north Atlantic and is rarely seen in British and Irish coastal waters in the summer months. Northern bottlenose whales have a gestation period of approximately 12 months. Calves are born between April and June, measuring 3.5 metres, and are dependent for over 12 months. The species is found in groups of 3 to 10, and feeds primarily on squid, but will also take other invertebrates, herring and deep sea fish.
Sperm whale (Physeter macrocephalus)
A pelagic species, measuring up to 20.5 metres in length, dark brown/grey in colour, with an elongated, rectangular head, a short lower jaw and no dorsal fin. This species is found occasionally in the north Atlantic and is rarely seen in British coastal waters in late summer and autumn. Sperm whales have a gestation period of 14.5 to 15 months, calves are born in summer and autumn, measuring 4.0 metres, and are dependent for up to 3.5 years. Females and calves are found in groups of 10 to 20 animals, but rarely venture above 45o North. Younger males are found in variable sized bachelor groups, older males are generally solitary. The diet is nearly exclusively squid (and octopus), although in some areas fish are also taken.
Minke whale (Balaenoptera acutorostrata)
A pelagic species of baleen whale measuring up to 8.5 metres in length, dark grey dorsally, pale grey/white ventrally, with a white band on the dorsal surface of the pectoral flippers. The dorsal fin is set well back, two thirds of the way along the back. This species is found in the north Atlantic and northern North Sea and is seen in British coastal waters mainly in the summer months. Minke whales have a gestation period of 10 months. Calves are born in winter, measuring 2.6 metres and are dependent for approximately 4 months. The species is found alone or in small groups, and they feed on krill and a variety of shoaling fish.
Sei Whale (Balaenoptera borealis):
A pelagic baleen whale, adults measure up to 16 metres and can live for 65 years. Often confused with the Fin whale but lacks the asymmetrical colouration of the lower jaw and baleen of the latter. Bluish or very dark grey dorsally, Sei have a paler grey or whitish underside and throat grooves, numbering 32-62, and a whitish lower fringe to the baleen. Pectoral fins are dark on both sides. The slender dorsal fin is more erect than a Fin whale’s and slightly further forward than other baleen whales. Sei whales can associate with Fin whales but are sporadic visitors to UK shores. Calves are born at 4.4-4.8 metres in the winter months, becoming sexually mature at 6-8 years old. Usually travelling alone or in pairs, they feed by surface skimming plankton, copepods and euphausiids (krill), and small shoaling fish.
Fin whale (Balaenoptera physalus):
A pelagic baleen whale and the second largest animal ever (second only to the Blue whale), adults can grow to more than 26 metres and live up to 90 years old. Having a silvery dark grey/brownish black upper body often with pale chevrons behind the blowholes, they have a proportionally small, sloping dorsal fin and a distinct ridge to their back showing down to the tail (hence also Razorback whale). Pectoral fins are usually dark on the top and lighter underneath. The best diagnostic is the asymmetrical colouration of their lower jaws and baleen; the right lower jaw and front right baleen is white to pale grey, while the left lower jaw and baleen is dark. Throat grooves number 56-100. Fin whales are born at 6-6.5 metres long, wean at 6-7 months and become sexually mature from 6 to 11 years. They feed on krill, small squid and fish such as mackerel, sprat and sand eel.
Humpback whale (Megaptera novaeangliae)
A pelagic species of baleen whale, measuring up to 15 metres in length. Black or dark grey dorsally, sometimes paler ventrally, with long, predominantly white pectoral flippers. The head is slender and covered in fleshy tubercles (lumps). The low dorsal fin is set well back on body. This species is found in the North Atlantic and is rarely seen on the Atlantic coasts in the spring and summer. Calves are born at just over 4 metres in length in the winter, after an approximately 11 month gestation period. The species is found in small groups and feeds on krill and a variety of shoaling fish.