The brain size of these mammals, the ability of dolphins to learn tricks and popular folklore have all contributed to the myth of the intelligent cetacean. However:

• The anatomy of whale brains is nothing exceptional. As well, the size and apparent complexity of the brains of these mammals is not a measure of intelligence.
• The tricks learned in captivity are often simply an extension of natural dolphin behaviour, similar to what a dog can do, for example.

A recent study of the common dolphin (Tursiops truncatus) demonstrated that these animals share with humans and monkeys a very rare trait in the animal world, namely the ability to recognize themselves in a mirror. Should we interpret this ability as a sign of exceptional intelligence?

Cetaceans are animals that are well adapted to the challenges of their natural environment. We are sometimes surprised by their behaviour because we still have a lot to learn about their lives.

To assume that they are more intelligent than other animals may prevent us from asking the right questions.

Sleeping in water is quite a challenge for a mammal that must breathe regularly! Studies conducted on captive dolphins have shown that half of their brains are resting while the other half remains awake to ensure breathing functions, which are volontary for cetaceans. As for their eyes, they kept them open, closing one or, rarely both. Dolphins living in groups keep one eye open allowing them to retain visual contact with the other dolphins in their group in order to synchronize their movements.

Do whales dream? Other, more recent studies on larger whales kept in captivity (belugas and grey whales) have demonstrated episodes of sleep lasting several minutes accompanied by convulsive movements or muscular spasms.These spasms resemble the nervous tics that accompany paradoxical sleep in terrestrial mammals, which is the stage of sleep associated with dreams. However, it is imposible to draw definite conclusions concerning the existence and length of this stage of sleep in cetaceans.

Resting periods are occasionally observed for whales in the wild. For example, belugas are sometimes spotted breathing slowly and floating immobile at the surface. This behaviour is referred to as logging as the whale resembles a floating log. This is without a doubt a resting period for them. Similar sightings have been noted for other species such as the humpback whale.

Other resting strategies are used by pinnipeds. Seals, for example, sleep and wake at regular intervals to come to the surface to breathe, while sea-lions adopt a special position while sleeping that allows them to keep their snout above the surface.

Sometimes whales are already dead when they become stranded on a beach. When a whale dies, it often tends to float up to the surface after a few days. The carcass is then transported by currents and tides and can come ashore on a beach.

Sometimes whales are still alive when they become stranded, most often when they are in groups. Several hypotheses have been put forward to explain these strandings that likely have multible causes. The whales could be sick or injured. Their sense of orientation can be affected by sickness or parasites. It is believed that whales use terrestrial magnetic field and coastal topography for orientation purposes. Thus, a disturbance of these magnetic fields or odd topography could lead to navigational errors. Typically, whales that are put back in the water return to shore and strand anew on the same beach. Their reference system may erroneously tell them that deeper water lies in this direction. Stranding of live animals often happen in the same place, in areas with specific characteristics. Pelagic species that are used to great oceanic depths may be caught by the tide in shallow estuaries. In the case of mass strandings, whales may be following a disoriented leader, or they could be swimming towards an animal that has already stranded and is emitting a distress call. In short, stranding remains a somewhat mysterious phenomenon.

There are as many answers to this question as there are migratory species. Migrations are often motivated by the need to find fertile feeding grounds. This could be the case for bowhead whales that swim to the Arctic in summer. Migrations may also be undertaken for breeding purposes. This is without a doubt what leads humpback whales to make the long journey in winter to the Caribbean and Hawaii. These large gatherings probably facilitate encounters between the sexes.

This is still unknown! Although there is still no definite answer, two hypotheses have been put forward to date:

• by the play of membranes and vibrating structures situated in the widening of the nasal passage between the skull and the blowhole
• in the larynx, by the vibration of structures similar to our vocal chords

Approximately 80 different species. Why ³approximately²? Certain species have only been observed on rare occasions while descriptions of others are based on but a few bone fragments. Still others form the basis of ongoing debate over classification. For example, the common dolphin (Tursiops truncatus or ³flipper²) could include several species or subspecies. Genetics should answer some of the more thorny questions on this subject. No modern-day species of cetacean has become extinct, however, several populations have disappeared.

As with all mammals, the whale calf grows inside the mother¹s uterus. A few sightings in the wild and several observations in captivity have allowed us to learn more about how they are born.

• They are generally born tail first, but can also come out head first.
• The newborn calf can start swimming, vocalizing, breathing and nursing right from birth.
• The mother and other adults of certain species undertake relatively intense physical contact with the newborn calf. For example, they may push the baby to the surface, swim rapidly around it or pin it between their bodies for several minutes following birth.

• Japan, which is a member of the International Whaling Commission (IWC), holds a permit for scientific hunting and takes several hundred minke whales each year.
• The United States, Denmark, Russia and the West Indian islands of St. Vincent and the Grenadines all have authorizations from the IWC to carry out subsistence hunting.
• Norway formulated an objection to the IWC moratorium and hunts several hundred minke whales each year in its waters.
• Canada, which pulled out of the IWC in 1982, regulates the subsistence hunting of belugas, narwhals and bowhead whales by indigenous peoples.
• Iceland, which also pulled out of the IWC, voted a 1999 resolution for the resumption of whaling in its territorial waters after a 10 year moratorium.