By recognizing whales as individuals we can learn a huge amount about their lives. Sperm whales have distinctive nicks and scars on the trailing edge of their tails (flukes) that persist throughout their lives and they can be recognized from photographs. This is known as photo-identification. By sharing photographs of the flukes of all the sperm whales they encounter in a central catalogue researchers can build up a picture of a whale's movements and its association with other whales. There are now over 3000 images of individual sperm whales in the North Atlantic and Mediterranean sperm whale catalogue and work is underway to develop computerized matching systems to help match each new photograph to the catalogue.

Another way to study sperm whales is by listening to the sounds that they make using hydrophones - underwater microphone. Sperm whales make loud, regular clicking sounds while they are submerged. These sounds are a form of sonar that allows the whales to navigate around the oceans and find their food. Listening to the sounds from the whales gives us the best idea of what they are doing when they are underwater. We can use this information to estimate whale numbers. Sometimes they make distinctive patterns of clicks called codas. These codas seem unique to groups of whales, sometimes referred to as clans, which reveals new information about the whales' social behaviour and relationships between different groups across the oceans. Another way of understanding relationships between individuals can be genetic (DNA analysis of collected skin samples).. Fortunately sperm whales naturally shed pieces of skin as they swim along and these can be collected using small nets.

Sperm whale behaviour includes socialising, foraging and resting. Group members spend much of the time dispersed but sometimes congregate to socialise, either lying quietly together at the surface, or actively touching and rubbing against each other while vocalising. Although mature males and females spend much of their lives apart, large males join nursery schools of females and calves for brief breeding periods between early winter and early summer; at these times they socialise with all members of the pod.

When you see a sperm whale 'fluke-up' (lift it's tail flukes clear of the water) it's usually about to start a deep foraging dive. These can last as long as 50 minutes and take the whale as deep as 800m in it its search for its favourite food - squid. When resting on the surface between dives, they take very deep breaths and then exhale four to six strong 'blows' each minute, creating plumes a few metres high.

Occasionally a sperm whale will propel itself out of the water, often clearing the surface with as much as two thirds of its body or more, and splashing down onto the water surface on it's back or side. We're still trying to understand the purpose of this 'breaching' behaviour.

-Russell