Taken From 'The Wild Dolphins Of Gibraltar - A Guide By Mike Lawrence'
Dolphins belong to a marine order called Cetacea (pronounced se-tay-shi-a) which is the group name given to those mammals that are born and live the whole of their lives in the sea. By definition this includes the Whale, Dolphin, Porpoise, Grampus and the Manatee, but would exclude such animals as the Seal and Walrus who have come on to land to give birth.
These are the family of whales that we all think of as being the largest, as indeed they are, in some cases growing to 120ft long and weighing up to 190 tons. In comparison, the Boeing B747 airliner weighs 150 tons when empty. They are distinguished from the other cetaceans, not by their size, but by the fact that they filter their food from the sea through curtains or plates of bristly substance called Baleen. This is found growing from the roof of their mouths, which are toothless and is extremely efficient in trapping small organisms from 1mm to about 75mm in size. Those organisms caught are chiefly Krill and Plankton and although very small, contain some of the richest sources of protein to be found on earth. This food is available in quantities of millions of tons in the oceans. One concentration found in the Antarctic was estimated to weigh 10,000,000 tons! The mysticeti filter this food up literally by the ton.
Are the group of cetaceans that include all the Toothed Whales, Grampus, Porpoise and Dolphins. Did you think that we would never get there? They all have teeth varying in number from 1 to over 200 and are the active hunters of the marine mammal world, unlike the Baleen Whales which slowly travel along vacuuming up their food. The odontoceti are not specialist feeders and individually eat a wider range of prey.
This control is affected through several peculiar properties of their skin. First of all the top layer is not dead, whereas ours is. When you vacuum the carpet and then empty the bag, you find a quantity of grey dust. We're sorry to tell you but most of that is dead human skin. Compared with cetaceans, we seem to have rather a bad case of dandruff!
In comparison their skin is alive, they have control over it and are able to "shiver" off the stagnant boundary layer that would otherwise slow them down. It is also slightly porous, the first two layers absorbing water and then expelling it, further lessening boundary layer drag and helping them to travel through water with less effort. Another factor affecting speed is shape. One of the first things yo notice about these creatures, apart from those that have fins, are that there are no projections or bumps. In fact it is quite hard to tell the sexes apart, as all the reproductive and mammary organs are kept within slits on the underside of the body. The design of the nuclear submarine is a good example of man copying one of nature's forms.
Cetaceans are the largest animals that have ever lived on earth. Why is this so? They live in an environment that is gravity free for all practical purposes. This was one of the reasons that the Dinosaurs and their kind never grew any larger. They could so easily get bogged down owing to their enormous weight. Circularity problems were another factor when sleeping on a particular part of the body, as the weight would compress the blood vessels in that part, thus cutting off it's blood supply. To avoid this, even today, most large land animals either catnap or sleep standing up. Cetaceans having solved the gravity problem were free to solve the next, which was that of heat loss.
Very small animals lose heat quickly because their surface area is large in comparison with their volume. This situation changes inversely as an animal gets larger. Terrestrial animals use a large part of their food intake to generate heat and so deep themselves warm. Next to the skin, cetaceans have a layer of fat called Blubber, to insulate them from the cooler water surrounding them and because of their large size, retain their heat more efficiently. Cetaceans that live in the Arctic regions, the Blue Whale for example, can weigh up to 190 tons and 40% of this weight is made up of blubber.
Like all other mammals, cetaceans are air breathers. In order to live in the sea, several important adaptations have taken place. The most obvious is the position of the nostrils or blow hole, which are no longer found at the end of the nose but on top of the head. This enables the animal to breathe in when the blow hole is above the water, at the same time allowing to keep his eyes and ears under the surface so that he can observe his surroundings.
The next time you see dolphins, try to see if you can fill your lungs in the same time that they can, as theirs are about the same size as ours. You'll find it very difficult, especially if you're swimming in a rough sea and you don't want to inhale water. The cetacean manages this little trick by having a very sensitive area around the blow hole, the most sensitive part on it's body and this senses the approach of a wave, triggering the closure of it before the water can enter. This automatic reflex enables them to sleep on the surface without inhaling water or waking up. All we can do in a similar situation is to hold our noses shut with our fingers, not an elegant solution to the problem.
When you examine the lungs of these animals, it becomes apparent that they are much more efficient than ours. To begin with we only fill ours to a third of their capacity, the cetaceans to about 90% of their possible volume. A further difference is in the construction of the lungs. The Aveoli, the very fine tubes in the lungs that carry oxygen over into the bloodstream, are more numerous in cetaceans than in any other species of mammal, thus enabling them to transfer more oxygen into their blood. This is further helped by an adaptation of the red blood cells themselves, which are larger and more numerous than in other animals and so enable them to transport more oxygen to the organs.
During deep dives, the circulatory system is modified by a slowing down of the heart rate and the re-routing of the blood supply from non-essential organs to the brain and locomotive muscles. The whole process allows some species to stay underwater for periods of up to 1 hour and to descend to depths of 10,000 ft. At this depth the pressure on their bodies is 2.5 tons over each square inch of their surface area.
You may wonder why they don't get crushed to death at these great depths or at least suffer the dreaded "divers bends". If you dive in sub aqua gear to more than about 30 ft underwater using compressed air to breathe, you cannot come straight back to the surface without stopping to decompress. The effect becomes more noticeable the farther down you go, until the time you have to spend coming up is far longer than the time you spent on the bottom. This is because under pressure, the nitrogen in the air you are breathing becomes dissolved in the blood. Conversely, on the way up, unless the time of ascent is long enough, the dissolved nitrogen in the bloodstream re-forms as bubbles before it can be re-processed in the lungs. These bubbles lodge in the joints and heart causing excruciating pain and in some cases death. Many of the diving deaths and injuries in the North Sea oil industry have been due to this cause. Cetaceans, because of their superb efficiency in breathing, do not have this problem. They need only one lungful of air to last them for a long period and there is not enough nitrogen in that lungful to cause this situation.
We are often asked, "if they are not breathing compressed air, why don't they get squeezed to death at pressures of up to 4500 lbs per sq inch?" Water is incompressible. All living creatures are chiefly composed of water, 90% in fact; the water pressure inside each cell of their bodies is equal to that outside.
"Surely if they open their mouths to feed at these depths, the water will rush in and drown them?" Yet again, it can't. The pressure is the same inside and outside and in any case, the respiratory system is separated from the mouth and digestive tract. Finally, there is one further modification to the respiratory system. When the lungs are full of air they are not able to withstand the enormous pressure upon them. The ribcage not being rigid, allows the ribs of the chest to be pushed in by the pressure until the lungs are completely collapsed, so reaching a state of equilibrium. During the ascend, with the release of pressure, the lungs return to normal.
Cetaceans evolved from a terrestrial creature and some remnants are left from that existence on land. First of all the front limbs are still apparent, but much modified. These flippers or lateral fins are not used for propelling the animal, but are used for balancing and inducing turns. They have an internal bone structure rather similar to our own hands with the exception of the thumb and this omission may well have played a vital part in the competition for dominance of the planet. The hind limbs have almost completely disappeared and are only represented in some species by two small bones unattached to the main skeleton.
Most cetaceans have good eye sight. You only have to go to a Dolphinarium to realise this when they are leaping though hoops, catching balls and performing tricks that call for a high level of co-ordination of body and eye. This was one of the senses that was developed on land and has not been impaired by living in the water. In fact the eyes have learned to adapt to the problems of refraction and distortion found in the two different mediums. Eyesight is not much help however when the visibility is no more than 60 or 60 feet, which it si in most places in the ocean. How do these animals find their food and each other? They all have an incredible sense of hearing. We now know that some of the larger cetaceans, the Humpback Whales for instance, can hear each other over distances well in excess of a thousand miles. The hearing range extends from about 20Hz to over 150kHz. The most expensive Hi-Fi has the performance of a Crystal set in comparison. The cetaceans have external ear channels about the size of a pin hole, but as these are usually blocked with wax they are not used to carry sounds to the inner ears. This is achieved by conduction along the lower jaws and is efficient enough to detect a pin dropped into a large pool.
The sense of touch is well developed. The skin of most cetaceans is very sensitive and you have only to ee the way they constantly touch each other to realise that this is so. Human beings receive a lot of information from this sense at an early age, by using the lips and then later on the tips of the fingers. The cetaceans, not having fingers, cannot receive information about texture and form by this method. It has been suggested that the male cetacean sometimes uses his penis for this purpose. In the case of the larger Baleen Whales the finger would be nearly 10ft long! The testes of the same species also weigh 1 ton each.
Of the other senses, it would appear that cetaceans do not have a sense of smell as the olfactory organs are not developed.
Cetaceans may be found in all the oceans of the world, but some individual species are not universally distributed because of their specialised diet. For instance, the great Baleen Whales do not migrate from one hemisphere to the other, but remain in the high latitudes where their food is usually found and have adapted to the seasonal availability of this food. During times of plenty, each one can be taking anything up to 4 tons of krill a day. This is sufficient to tide them over periods of scarcity which may last for several months.
It is only in a few instances that this rule does not apply, namely the species of dolphin that live in fresh water. They are to be found in such rivers as the Amazon, Indus and Ganges and represent a specialised form, as they rely more on their sonar than other dolphins and in some cases have become totally blind.
Dolphins, such as the Common Dolphin, may be found virtually anywhere and are especially prevalent in the Mediterranean. These are the ones that have been known to man for thousands of years. Indeed the story of how the poet Arion was rescued from pirates 600 years before Christ, shows how long man and dolphins have had an affinity for each other.
The Straits of Gibraltar are one of the great natural land bridges of the world and are famous for the biannual migration of bird life. What is generally not so realised, is that there is a continual passage of cetaceans passing between the Mediterranean and the Atlantic. It is certain that the Straits are monitored by NATO listening devices. It would be of invaluable assistance to marine biologists to know what record, if any, is kept of cetacean movements which are much noisier than those sounds created by submarines.
It is only in comparatively recent geological times that all this marine movement has become possible. Twelve million years ago, Africa slowly bumped into Spain and a low mountain ridge was formed between Tangier and Tarifa. The Mediterranean became a vast lake eventually drying up, leaving vast deposits of salt behind. Six million years later, Africa started to retreat from Europe and a breach was created in the mountain dam previously formed. The largest waterfall the world has ever known was created. For a hundred years, the Atlantic thundered over a 3000 ft drop, yet again filling the Mediterranean basin, thus allowing the reintroduction of marine life into this area.
Because the Straits are only 13 miles wide at their narrowest point, the concentration of cetaceans is very high, especially so towards the middle. It is about 3 miles offshore that you find the larger examples, such as the Sperm Whale. For some reason most sightings show that they are heading in a westerly direction. The prevailing surface current is easterly and these animals may be just stemming the current flow and not in fact travelling out of the Straits at that particular time.
From prominent headlands, with patience and binoculars, it is possible to see the smaller cetaceans closer inshore. In the Bay of Gibraltar, Common and Striped dolphins are always present.
Cetaceans are mainly social animals, they are not solitary but spend all of their lives together in groups of varying numbers ranging from a family of three to many hundreds. Because the oceans are so bountiful, the cetacean population was very large. Unfortunately today, the situation is rather different. Modern methods of hunting have decimated some species to the point of virtual extinction, as in the case of the Baleen Whales. Even if all whale hunting was stopped now, it would take over a hundred years for some members of the mysticeti to significantly increase their numbers. Once a population drops below a certain figure the chances of finding a mate are significantly reduced, this is doubly so for Cetaceans who live in the immensity of the oceans. Cetaceans are slow breeders, only producing one offspring at a time, usually every other year and even the shortest lived do not start breeding until they are about five years old.
We have discussed the incredible hearing of these creatures before and now it is perhaps time to go into some aspects of their speech. Cetaceans produce sounds by passing air through various passageways in the head, but unlike other animals, for reasons that may now be apparent to you, do not actually expel air when they are vocalising. The air is only being transferred from one cavity to another within the head and it is though that the prominent bulge displayed on the forehead of some species, acts as a lens concentrating the sound waves into a beam. These 20-Hz low frequency sounds can be heard over hundreds of miles between some of the mysticeti and are the only means of communication between them.
Some of you may have heard a ballad that was often played on the radio a few years ago which featured the song of the Humpback Whale. It had a lovely haunting real whale accompaniment. What in fact you were listening to was the mating call of this animal. It is a very peculiar fact, but the song of the Humpback Whale may last as long as 30 minutes without any repetition of the words at all. During a period of several weeks the singing, which may last for twenty four hours at a time, is gradually changed, each whale composing his own special version.
Once having found a suitable mate, the male cetacean puts on a display of diving and leaping that has to be seen to be believed. Right alongside the boat, we have seen Pilot Whales leaping as high as 12-15 ft out of the water during such a display. The object seems to be to make the biggest splash possible, the sound carrying a great distance underwater as the impact is in the region of 2 tons. Eventually the female joins in, the two quite literally making high speed passes at each other. Gradually they come into physical contact, swimming belly to belly, sometimes with their flippers around each other, this still being part of the courtship. The actual method of mating varies from species to species, some couples remaining stationary in the water in a vertical position whilst others are horizontal. In some cases they may involve a very close friend on the other side of the female to keep her pushed against the male!
The reproductive organs of cetaceans are not visible externally, but for better streamlining are kept within slits in the body; the male's some distance from the vent, the female's in close proximity. In her case the two mammaries are also enclosed, and are in the same area. Coition lasts for about 30 seconds, which may not seem very long, but the cetacean is a very sexually active animal and may mate a dozen times a day. It is also interesting to note that this high level of sexuality is unusual in animals apart from man. We are afraid to say that in the case of the Common Dolphins they are not too selective in choosing an object for their sexual gratification. We have seen males chasing males and other immature dolphins. The male dolphin is able to indulge in this high level of sexual activity, as he has a muscular erected penis which he can erect at will.
In the film "Ride a Wild Dolphin" shown by Yorkshire TV there is a lovely episode, where Maura Mitchell is approached by Donald the Dolphin who appears to be sexually aroused. One cannot say whether he was attracted by her femininity or because he wanted to examine the texture of her wetsuit in the only way he could. However ladies, if you are ever approached by a friendly dolphin whilst swimming, please remember that they are classed as Royal Fish and belong to the Crown. Complaints to Buck House please!
The gestation period of cetaceans varies between 10 and 16 months. This is quite a short time for what can be a very large animal and the foetus has to develop very rapidly. It also has to be remembered that the new born baby is being born into a very hostile environment and has to be completely formed and ready to swim alongside his mother immediately. The trauma of being born is quite a shock to all warm blooded animals and this must be doubly so for the cetacean, who after emerging from the warm birth canal, finds that he is in very cold surroundings and cannot breathe.
Cetacean births are usually breach presented to enable the baby to stay inside the mother for as long as possible until the process is completed. In some cases, upon separation, the mother is assisted by other females who have been in attendance during the birth, one or more of which will help to bring the newborn baby to the surface and start it breathing. When this is achieved and the mother is sufficiently recovered, she takes over and starts suckling her offspring. The baby at the time of birth is about a quarter to a third of its mother's length.
Cetacean milk is some of the richest in the animal world, comprising up to 40% fat content. The mother feeds her offspring by erecting a nipple from within the mammary fold and injecting the milk under high pressure into the baby's mouth, enabling it to receive large quantities in between coming up to the surface to breathe.
The Bay of Gibraltar seems to be a favourite place for nursery schools of Common Dolphin and on one occasion we witnessed the birth of a dolphin in the wild. It is a very common sight to see baby dolphins accompanied by their mothers who always stay very close to them, rising to the surface a few inches away from each other when coming up to breathe. From our observations in the Bay of Gibraltar, there does not seem to be a set season for giving birth because young of only a few days old are present throughout the year.
Lactation lasts for about 12 months, after which the weaning process is started. In the case of the Odontoceti, the mother bites off the head of small fish and offers the carcass to the young animal. This technique is used in Dolphinaria to induce newly captured dolphins to feed, as they will generally not take dead fish but do have a childhood memory that such food was offered to them by their mothers. About five years later, a new generation of dolphins are starting to breed.
The mysticeti are the vacuum cleaners of the marine world, scooping up huge quantities of food, chiefly plankton and krill, both of which are some of the richest sources of protein available. You can try catching this for yourself with a very fine net when you next visit the sea. After dragging it through the water for some minutes, you will find a minute quantity of a jellylike substance in the bottom of the net. This is plankton and on examination with a powerful magnifying glass, is seen to be composed of minute plants and animals. If Jonah found himself in the stomach of a whale it certainly was not one of the group mysticeti, which can only swallow objects of a few centimetres in size. It is interesting to note that Dr. Alan Bombard fed himself mostly on this substance while crossing the Atlantic in the rubber dinghy "Le Herotic", the fresh water in the plankton augmenting his water supply. Krill is composed of larger creatures such as very small shrimps etc.
Most of the odontoceti seem to hunt in an organised manner. We have seen a large shoal of Garfish corralled into a compact group by about a dozen dolphins, who were taking it in turns to swim through them at high speed and catching several before coming out on the other side. Flying Fish are another favourite food of the dolphin and provide a good example of the contest between creatures that ultimately influences their development. The flying fish has learnt to fly to escape from predators and can travel long distances down wind at high speed. The dolphin however, has learnt to swim even faster and is invariably awaiting the fishes re-entry into the water with the inevitable result. If you want to see a dolphin swimming really fast, then this is the time to do so. It also demonstrates how well they can see out of the water.
Dogs live in a world that is painted in pictures of smell. You only have to see how a dog stops at every lamp post and how they greet each other to realise that this is so. Most of their foraging for food relies on this sense and is most effective when the animal is down wind from its quarry.
The cetacean world however has to be painted in terms of sound, because the medium they live in has poor visibility and total darkness at great depths. Sound has a further advantage that underwater it is not dependent on the direction of currents and carries enormous distances. When used with an extremely well developed sense of hearing, it can provide cetaceans with a great deal of information about their surroundings.
Cetaceans find their food by using sonar in the same way as bats do. They emit a series of high pitched clicks or squeaks and then wait for the echo to return. The direction and time taken for this return supplies them with the information as to the bearing and distance from them. Not only this, but because they can vary the frequency and power of the sound beam, they can receive further information as to size, shape and density of the object being scanned. Consequently, when a Sperm Whale is many thousands of feet below the surface on the sea bed in total darkness, he is still able to find the squid upon which he feeds.
Possibly one of the reasons that a powerful animal like the Orca does not attack humans in the water, even though we might be wearing a black wet suit and look rather similar to a seal, may well be that his sonar informs him that we are a very different air-breathing creature. The air escaping from the relief valve of the scuba gear and the echo from the metal air tanks inform him of this fact. This was confirmed during a conversation we had last year with BBC cameraman Martin Saunders, who had filmed with the Killer Whale in the open sea.
We are now starting to see that the cetaceans are a special and very unusual life form. They may collectively take large quantities of food from the sea but this has not been a problem until recently. Man with modern methods of fishing is now gradually emptying the oceans of their fish stocks. Some countries have misguidedly sought the solution to this problem by trying to eliminate the cetaceans that are to be found in their waters, namely Japan and some of those countries around the edge of the Black Sea. Even if all the cetaceans were eliminated, there would still have to be stringent controls over quotas and stocks, as there would still not be enough to supply world demand. It would appear that a possible solution to this problem could be a much higher emphasis on fish farming, thus helping to preserve the only other creature, apart from man, that has an intelligent consciousness. In the next part of this guide we shall be discussing this intelligence.
What is intelligence? We call ourselves the most intelligent species on the planet and yet we have wars, poverty, oppression and the squandering of natural resources. The list is endless. Obviously, intelligence is not always measured in terms of a creatures ability to manipulate events and surroundings, for what at the time, it considers to be in its best interests. In the final analysis we may be equating intelligence with survival, which in the case of mankind today is no more assured than that of the flea!
Most of us have very similar thought processes. For instance, it is quite easy to visualise three billiard balls in a straight line on a green table without splitting them into groups. Try increasing the number to five and it becomes more difficult not to see them as one group of three and one of two, or one of four and one. The whole process becomes harder as you increase the number of balls in the line. The reason is that our brains are only programmed to work in a certain way. In this case it illustrates that the human thinking process tries to place objects in mathematical blocks or patterns. If the cetaceans do not have this programme, does that mean that they are not intelligent? No. It just means that they have different thought processes. For instance, we have seen a Common Dolphin caught by the simple means of drawing a net around him on the surface of the water. He could easily have jumped over it, but he just could not think in this particular pattern.
It would appear that in some instances however, that they can adapt to out methods of thinking. Some dolphins, who are natural mimics, have been taught to mimic human speech out of water. Not in the way that a parrot does but using words in context to pass information. In our discussion, we may well find that we are not so very far ahead of the dolphin mentally. Is perhaps our big brain the answer to our supposed superiority? The elephant has a larger brain than man and yet we would not say that the elephant is as intelligent as we are. The dolphin brain does have one physical characteristic that is as developed as ours, if not more so, and that is the cerebral cortex.
The cerebral cortex in man is understood to be the part of the brain that controls the higher thought processes, such as reasoning, behaviour, social attitudes and learning. In man it is extremely well developed, having many convolutions and a large surface area with many neurons. If we examine the brain of the dolphin, we find that although the brain is a different shape to fit into a streamlined skull, it has the same weight as ours. He also has the same brain to body weight ratio as ourselves, the highest in the animal kingdom, yet again, with an equally developed cortex. In other words "THE COMPUTER IS AS GOOD AS OURS". Perhaps we should now be talking about the potential for intelligence only as we understand it.
We saw earlier that cetaceans evolved from a land animal and have been living in the sea for about 25 million years. Having physically adapted to this change, there was little pressure to evolve further in the face of a bountiful existence. Those challenges available were chiefly of a social nature and the first amongst these was speech. We have seen how vocal cetaceans are. This is not of the same order for instance, as bird song which is usually to attract a mate or to stake out territory.
Cetaceans seem to delight in making sounds that when carefully analysed, are not repetitive and the more of them present, the more vocal they become, rather like a school outing.
An examination of the brain shows that the speech centres are indeed well developed and it is difficult not to conclude that some form of verbal interchange of information is taking place. Unfortunately, no one so far has managed to decipher this language, if it is one, although it is good practice for when we meet the little green men from outer space. NASA have spent large sums of money researching with dolphins as an exercise in communicating with an alien intelligence. If dolphins do have a language that we could understand and it seems with the help of computers that one day we may be able to, the amount of information we could receive, if put to the right use, would be absolutely invaluable.
Another manifestation of dolphin intelligence are the social structures that they have set up. These are not similar to the ones that you find in bees or ants, as these have been genetically programmed to behave in a certain way. Dolphins can adapt to constantly changing situations. This has been one of the problems when studying them in captivity, as their behaviour is considerably modified under these circumstances, as our is, when kept in overcrowded and confined quarters.
Dolphin intelligence seems to be directed along paths of enjoyment, which in themselves do not bring a physical reward, but are rewarding mentally and in some cases appear to involve a sense of humour. We were at "Sea World" in Florida a few years ago and were back stage with a group of Bottle Nosed Dolphins. Before they would come and make friends, we had to perform tricks for them, which in this case consisted of getting a leaf from the other side of the pool and bringing it back to them. The dog and stick game, but played the other way around; we were the dog!
On another occasion, just before a performance, the dolphins hid all the equipment they use under a ledge at the bottom of the pool and a diver had to go down to retrieve it before the act could start. Again in the Bay of Gibraltar we have seen a group of 50 dolphins taking it in turns to race around a circular path of about half a mile in diameter. This went on for an hour with much boisterous leaping and splashing and was nothing to do with feeding or mating, but appeared to be some sort of contest. Dolphin Olympics? All this shows that these creatures require a large degree of mental stimulation and perhaps the big train is being developed for the purpose of enjoyment.
Dolphins require the presence of another intelligent companion, it is not possible to keep them in captivity on their own. Indeed, in the solitary state they will just switch off and die in a matter of a few hours for no apparent physical reason. When dolphins are transported from one Dolphinarium to another, it is necessary to have a human companion who will quietly talk to them and gently touch them for the whole of the journey. This is also part of the routine of trying to help a stranded cetacean on a beach.
They seem to have an awareness of social obligation towards each other and we have seen an injured animal being supported on the surface by others to enable it to breathe. This awareness also extends to other creatures and there are many authentic cases of them aiding human beings in distress when they are in the water. There are also stories of dolphins helping man to catch fish, some of which go back to the days of the Roman writer Pliny who lived in the first century AD. In modern times, off the coast of Mauritania, there is filmed evidence of dolphins rounding up fish to enable fishermen to catch them without any reward to the dolphins.
The primitive ancestors of man appeared about 25 million years ago in the form of a small monkey-like creature. At this time the dolphin was starting to evolve and in another 12 million years was equipped with a large brain. Man would have to wait a further 9 million years before reaching this level. One would think that with this start the dolphin would now be the dominant creature on Earth. Instead man has achieved this position because of four related factors which are:
The dolphin has the first three of the necessary requirements and it is only in the last, the ability to make tools, that he is deficient. It would appear that man has only achieved his pre-eminence on Earth by the last of these gifts, "AN OPPOSABLE THUMB". The more he fashioned objects, the more he exercised his brain, the more he exercised his brain, the more complicated these tools became. The process is still continuing and now for the first time, a living creature has the power to totally destroy its own kind everywhere on the planet in the course of a single day. This may seem a little heavy, but the more one comes into contact with cetaceans, whether in captivity or in the wild, one cannot help but compare their social attitudes to those of man. In the long term the Cetacean may yet become Earth's most successful species.
Visitors to the Straits of Gibraltar
The largest of the toothed cetaceans, which is distinguished by the enormous head a third of the body length. There is no pronounced dorsal fin except for a small bump 2/3 along the back followed by a series of smaller ones towards the tail. The lateral fins are short and stubby. The overall colour is a dark greyish brown with lighter patches indiscriminately placed and becoming more prominent with age. This is the Great White Whale that featured in Melville's book "Moby Dick". Able to dive to depths of 10,000 ft. and remain submerged for periods of up to an hour and a half where it feeds on giant squid. To the tune of a ton a day!
The Humpback Whale
Easily recognised by the extremely long white lateral fins and vertically held tail with white underside, seen when it sounds. A further means of identification is the balloon of spray when it blows.
Feeds mainly, when in Gibraltar, on anchovies and small fish, consuming about 5 cwt a day. Thanks to commercial whaling there are about 1500 left in the North Atlantic and possibly only 5000 in the whole world!
The Killer Whale
False Killer Whale
Length: 18 ft.
Long Fin Pilot Whale
Length: 20 ft.
Length: 7-8 ft.
The Striped Dolphin
Length: 6-8 ft.
In all respects very similar to the Common Dolphin but slightly more slender and instead of the hour glass or saddle pattern, the top half is uniformly dark and is divided from the lighter bottom half by a prominent dark line running from eye to vent. Very common in the Bay of Gibraltar where they feed on Sardines and Shrimps.
Bottle Nosed Dolphin
These are the dolphins that we have all seen in Dolphinaria and on TV. They also have been known to mankind for many thousands of years. In recent times there have been reports of them appearing off beaches along the south coast of England and giving rides to children. They have a prominent beak. The dorsal fin is prominent and recurved, the lateral fins being strong in appearance and of average size. Colour is blue grey and varies from light to dark. They will eat most forms of fish life found in the sea in quantities up to 25 lbs a day.
The following vantage points on land, offer a chance to observe cetaceans in the wild.
Europa Pt. In strong easterlies where they often play in the surf.
SE off Punta Carnero on the Western side of the Bay.
At the Northern end of the Bay, close inshore to the western side of the oil refinery. (See general map)
We hope that all of the foregoing will be of interest and help to those of you who may wish to see these lovely animals in their natural habitat. We have tried to answer those questions that we are most often asked, when running excursions in the Bay of Gibraltar on board the "Dolphin Safari".
Lyall Watson. Whales of the World. Hutchinson and Co.