Orca, sometimes known as killer whales, are actually the largest members of the dolphin family. They have black backs and white patterns on their stomachs. Males have a large triangular dorsal fin, while females have a shorter curved fin.
Orca live in small family groups or pods of up to 30 individuals, although pods tend to be smaller in New Zealand waters.
Adult orca have an extremely diverse diet including all kinds of fish, sharks, rays, squid, birds and turtles. They are the only known cetaceans that regularly prey upon other marine mammals – when they arrive in the Bay the dolphins usually skip town for the day! Orca hunt cooperatively and are even known to intentionally ‘strand’ themselves on beaches in order to catch seals. There is no record of orca attacking humans.
Newborns grow to 2.1-2.5m, 180kgs. Adult to 5.5-9.8m, 2.6-9 tons!
Bryde’s (pronounced "broodus") whales have a bluish-gray body with white on the underside. They have very broad and short head with relatively large eyes. Females are slightly larger than males.
The Bryde’s whale has two narrow blowholes that can blow up to 4m high. It has no teeth but has two rows of baleen plates, which are similar to bristles, which it uses to filter and trap small fish like anchovy, herring and mackerel.
They are usually found alone or in pairs, but will sometimes gather in pods of up to 30 at good feeding grounds. They can dive for 5 – 15 minutes at a time and will follow up a dive with a series of blows.
The pilot whale, like the orca whale, is a member of the dolphin family, and is second only to the killer whale in size. Pilot whales have stocky bodies and a distinctive rounded head with a slight beak and up-curved mouth. They are usually dark grey or black in colour, and often have a saddle-like marking behind their dorsal fin, which is set forward on the back and sweeps back.
Pilot whales mainly feed on squid, but will eat fish as well. A pilot whale has only 40 to 48 teeth, compared to 120 in many other dolphin species. This may indicate an evolutionary trend towards fewer teeth as a squid eater. Life span is about 45 years in males and 60 years in females for both species.
Pilot whales are very social and are often found in groups of 10 to 30 in number on average but some groups may be 100 or more. They are quite active and will frequently approach boats.
Size: 4– 8m; 1.5–3.8t
The blue whale is the largest mammal, possibly the largest animal, to ever inhabit the earth. It has a flat U-shaped head and a long tapering body with a small dorsal fin. Female blue whales are larger than males of the same age.
Blue whales have twin blowholes and a lung capacity of 5,000 litres. When breathing, they send up a spectacular vertical spray of up to 12 metres that can be seen from a great distance on a calm day. Their flippers are 3–4 metres long, helping them reach speeds of up to 50 kilometres per hour. When feeding they slow down to 5 kilometres per hour and can eat up to 40 million krill (small crustaceans) a day.
Blue whales usually travel alone or with one other individual. They do not form the large close-knit groups seen in other baleen whale species, but will gather in large numbers where there is plenty of food.
In its first seven months, a blue whale calf drinks approximately 400 litres of milk every day and puts on up to 90 kilogrammes per day. At birth a blue whale can weigh up to 2,700 kilogrammes.
Before the whaling industry there were estimated to be more than 350,000 blue whales worldwide, but up to 99% of the population were slaughtered. Presently, there are an estimated 5,000 to 10,000 blue whales in the Southern Hemisphere.
Size: 23–30m; 100–120t
Humpback whales are easily identified with their knobbly heads, long flippers with broad flukes, and short humped dorsal fins. Their body and flippers are coloured blue-black to dark grey with partially white undersides. Humpbacks are well known for their spectacular ‘breaching’ activity, leaping out of the water and slapping the water with their fins.
Between migrations humpback whales spend much of their time fairly close to the shore. They are frequent visitors to New Zealand’s coastal waters on their long migration routes, between their feeding grounds in the Balleny Islands near Antarctica and the breeding area further north. They travel mainly along the east coast during autumn and return along the west coast during spring, sometimes passing through Cook Strait.
Humpbacks only feed during summer. They are baleen feeders, eating krill and small schooling fish like mackerel and herring. They have a range of interesting feeding techniques, including lunging through patches of fish, stunning prey with their flippers and blowing “bubble-nets” to trap them.
Size: Newborns 3–4.5m and 1 tonne, Adults 11.5–16m and 25–40 tonnes