Killer whales, like orcas, are actually dolphins, not whales. They are generally smaller than pilot whales and orcas (killer whales) but larger than other 'dolphins'. They have a dark body colour with a long, slender head that tapers to a rounded beak. The fins on their backs are large with either a pointed or rounded tip. They quite often have scars on parts of their bodies. Their flukes are small in relation to the rest of their bodies. Their flippers are different to many other whales in that they have a unique 'elbow', like that of the long-finned pilot whale.

Finless porpoises are one of the smallest cetaceans. They are pale grey-blue in colour with a small mouth that curves slightly upwards and a slight depression behind the blowhole. They are the only porpoises to have a bulbous melon. Instead of a fin, they have a ridge along their backs which runs from above the flippers to the beginning of their tail stock. This ridge is covered in circular wart-like tubercles or bumps.

Finless porpoises are quite active animals, usually swimming just beneath the surface with sudden, darting movements. They cause little disturbance when they rise to the surface, and they tend to roll onto their sides when doing so. They have been known to spyhop, but are rarely seen breaching.

Indo-Pacific humpback dolphins can vary in colour from yellow to pink to almost white to medium grey; their bellies are usually the lightest areas. They also have a broad-based dorsal fin that slopes backwards. Those found in the west have a fatty hump which the dorsal fin sits on, those in the east don't have a hump and they can sometimes get confused with bottlenose dolphins.

These dolphins are slow swimming animals that avoid boats if possible and rarely bow-ride. They display many aerial behaviours; often breaching, lob tailing and spyhops. They even lie on their sides and wave their flippers! Although wary of boats, they do associate readily with other species, especially bottlenose dolphins.

Killer whales (orcas) are large, stocky, and heavy! Their jet black, white and grey markings, and the males' very tall dorsal fin, make them hard to muddle up with other species. In fact, a male's dorsal fin can be as tall as a man, up to 1.8m (6ft) high! It is the tallest dorsal fin in the animal kingdom. Females have a much smaller fin, theirs is only about half the size and is more curved.

Young calves can be a little trickier to identify as their saddle-patch (the patch behind the dorsal fin) can be quite dark and therefore blend into the rest of their bodies; and their light patches (behind the eyes and on the belly) can look a bit pink or rusty coloured. Researchers use the dorsal fins to identify individual orcas. Saddle-patches are also unique to individual whales, no two orcas have exactly the same saddle-patch shape and pattern. An orca has between 20 and 26 large sharp teeth in both upper and lower jaws; these curve backwards towards the throat and interlock when the whale closes its mouth. They are perfectly designed for catching and biting their food.

Risso's dolphins are quite easy to identify, especially when they get older. This is because they become scarred and battered due to being scratched by the teeth of other Risso's dolphins. They only have teeth in the front of their lower jaw and these are used when playing or fighting. When born they are grey all over, and then become chocolate-brown and eventually pale grey with a pale underside.

Their flippers and tail remain darker though, and the flukes are broad with pointed tips. They have a very tall dorsal fin which can be up to 50cm in length, the tip of which may be curved or pointed. Instead of a beak, it has a blunt head with bulging forehead that slopes steeply to the mouth which curves upwards.

Risso's do not often 'bow- ride' in front of boats, but may swim beside or in the bubbly wake that a boat leaves. They generally swim in groups of between 3 and 50 animals. These groups spread out in a long line when hunting for food. Young animals are energetic, and may breach (lift themselves out of the water), slap their flippers against the surface of the sea, ‘spyhop’ (lift their head above the surface to have a look around), and surf in the waves.

There are a number of different varieties of Spinner dolphins, each with slightly different body shapes, colours and sizes. They all have long, slender beaks and tall upright dorsal fins. They have a small notch in their flukes. Most of them have three tones of colour, with a dark top through to a light belly. Oman Spinner dolphin have three very distinct colour patches and the underside is almost completely white. They all have long, pointed flippers and gently sloping foreheads with a crease where it joins the beak.

Spinner dolphins are extremely acrobatic and are famous for leaping out of the water and spinning in mid-air. Along with the short-snouted spinner dolphins, they are the only species of dolphin known to "spin". They throw themselves up to 3m (9ft 9in) into the air and twist their bodies, spinning round longitudinally up to 7 times in a single leap! They also breach in the more normal manner. They live in large groups and are sometimes seen with pantropical spotted dolphins, yellowfin tuna and seabirds. Short-snouted spinner dolphins were once considered to be a variation of the long-snouted spinner dolphins. They were officially classified as a separate species in 1981.

There are two different forms of pantropical spotted dolphins; coastal and offshore. The coastal dolphins are larger with thicker beaks and more spots. You would think that spotted dolphins would be easy to identify, but sometimes they don't have many spots. When they are born they have no spots, so it is easy to get them muddled up with other dolphins such as the bottlenose. Pantropical spotted dolphins are very similar to Atlantic spotted dolphins. They have a dark grey cape on the top of their body, then a lighter grey area along the middle of the body and a pale grey underside. They have light spots on their dark skin and dark spots on their light skin. Their beaks are long and thin with a dark patch on top which goes back in a stripe around the eye. They also have a dark stripe going from under their mouth to their flippers which are dark too. Pantropical spotted dolphins have small flippers with pointed tips, sickle-shaped dorsal fins and a notch in their flukes which also have pointed tips. They have 70-96 teeth in their upper jaw and 68-94 in their lower jaw.

 Pantropical spotted dolphins are very fast swimmers and enjoy leaping out of the water. They will often bow-ride, breach and lob-tail. They live in large groups of up to 1000 individuals, though the coastal populations are more likely to be seen in smaller groups. Some pantropical spotted dolphins develop so many spots that the background colour can not be seen. The top of their bodies becomes very pale with all the spots and they are nicknamed "Silverbacks".

The striped dolphin is fairly easy to identify from the distinctive strips on its sides and the pink undersides of some. One of its distinctive features is the pale grey, finger-shaped marking below the dorsal fin. The other unique feature is a black line that stretches from beak, around the eye patch to the underside of the rear flank. These features are easily seem when they race along with flying leaps. The striped dolphin is very streamlined with a long beak and large dorsal fin.

 They are very agile and highly active, often spotted tail-spinning and somersaulting as well as breaching to spectacular heights (7m.). They bow-ride as well but, strangely, it seems mainly in the Atlantic Ocean, there are far fewer reports of this in the Pacific and Indian Oceans. They form large social groups of between 10 - 500 but can be found in schools of up to 3000! When swimming in such large groups, approximately one-third of the members can be seen above the surface at any one time.