The beaked whales are one of the most specialized and least understood of all the mammal groups. Majority of the people do not understand much about simple freshwater aquarium creatures like shrimps, so when it comes to whales their knowledge gets even badder. The world they inhabit is at the edge of our understanding, even in the 21st century it remains almost universally beyond our reach. To try and picture the world of a beaked whale imagine yourself sat in a hot air balloon a kilometer or two high. This is where you get the air to breathe. Below you the air is wrong – try to breath and you would suffocate and die, but the food you need survive is down there, 900 meters below. The only option is to take a deep breath and descend, tie a rope around your waist so you can come back up, then jump over the side and drop.
By the time you get to the bottom, it’s dark; even if it is bright as a sunny summer’s day at the balloon above, it’s dark as a cloudy winter’s night down here, and its freezing cold. Now that you’re here there’s no time to waste, its time to
This isn’t an empty landscape; you’re in a deep valley or hovering off the edge of a cliff. This is where food is most abundant, concentrated by currents and physical barriers, but the food won’t come to you, you have to go find it. So you search, casting your torch beam around. When you illuminate that object you then have to decide what it is, dinner or danger? If it’s the former, you still have to catch it. You don’t eat food that stands still, but rather fish and squid which can fly through these water plants, mosses, dark depths with all the speed, skill and control of swifts and swallows, and if your target gets out of your torch beam of sound you’ve lost it. When you find something edible you have to chase it down. Sometimes you miss but other times you catch your prey, but not using your hands (you don’t have any) or your teeth (even if you have them they are no use in feeding) but by sucking. Whale mouth works like a filter. You’ve come all this way to suck your dinner, which means you only eat food that’s small enough to succumb to the power of your throat muscles, and one meal is not enough you need to feed again and again each dive. Still holding your breath?
For an hour or more you carry on this cat and dog chase through the permanent darkness, but eventually, you do need air again, so you start to climb back up your rope. Remember the breathable air is 900 meters above you – just to breath again you need to climb a mountain. When you reach the safety of the balloon you can breathe, refuel your lungs, maybe socialize for a bit, but when you’re hungry there is only one place to get food and you have to drop again into the depths.
That’s something like the world of a beaked whale, that’s what it means to be a member of one of the most specialized families of mammals in the world. Of
To cope with this lifestyle the beaked whales have evolved a whole suite of specialisms. Some they share with other deep diving species – lungs that crush almost completely on diving, blood designed to carry enhanced amounts of oxygen around the body, a circulation system that isolates organs that aren’t needed at depth so that oxygen can be rationed and behaviours to mitigate for the debilitating effects of the bends. We know of some other weird and wonderful adaptations such as a specialised throat structure to allow strong sucking, teeth that are good for fighting over mates but nothing else, and pockets to tuck flippers into to swim more efficiently, others we can only guess at. Why have the densest bones of any mammal? Why have 13 stomachs?
Whatever the purpose of these adaptations, they work. With 21 species described to
Cuvier’s Beaked Whale (Ziphius cavirostris)
One of the most frequently sighted and probably most abundant beaked whales. A regular presence in European waters and throughout the temperate oceans of the world. Locally abundant in water more than 1,000m deep and especially in areas with depth variation like underwater escarpments and the continental shelf.
It is one of the most striking members of the family with bold markings ranging from a yellowish- grey to brick red. Most of the body is typically a warm orangey-brown with a paler head. There is usually a darker patch around the eye. As the animals mature the extent of this pale pigmentation increases, gradually forming a cape that stretches back to the dorsal fin.
Adult males have a pair of teeth that protrude from the tip of the lower jaw and are usually covered in scars from the teeth of other males. In addition to this scratching the species also some times
Curvier’s beaked whale is one of the
Cuvier’s beaked whales are sometimes sighted alone and it’s likely that single animals are mature males, indicated by heavy scarring. On other occasions they are encountered in groups of two to eight (up to 25 have been rarely recorded). These groups often appear to be of mixed composition, with at least one adult male and adult females. It does seem that females usually leave mixed sex pods to raise their young. The species feeds on deep sea fish and squid and probably dives for an hour or more to considerable depths to forage. They are often seen logging or swimming slowly at the surface, perhaps resting after a deeper dive. They are general undemonstrative but have been seen breaching on numerous occasions.
Perrin’s Beaked Whale (Mesoplodon perrini)
This is the most recently described of the beaked whales. Its true identity only being
Arnoux’s Beaked Whale (Berardius arnuxii)
The second largest beaked whale, Arnoux’s is probably the most southernmost ranging of the family. The northern limit of its range is at about 34°S and from there it ranges to the edge of the Antarctic pack ice and beyond – it is regularly found in open leads in the pack ice 50km or more from the open sea. Although rarely observed in the open ocean the occurrence of individuals in confined space of ice leads has allowed some opportunistic studies of their behaviour. This appears to be a fairly sociable species (like its northern hemisphere counterpart Baird’s beaked whale) – with no aggression being recorded between individuals even in confined surroundings. A typical dive appears to be about 40 minutes, and may be up to 70 minutes in duration. On average they surface for between 1.2 and 6.8 minutes and breath at a rate of 9.6 breaths per minute – about once every 6 seconds. Of 30 animals closely examined in ice leads 11 were toothless, 16 had one pair of teeth and 3 had two pairs (always in the lower jaw) but how this related to the age and sex of the animals involved isn’t known. Given its range this species appears able to exploit a feeding niche under the pack ice.
Andrews’ Beaked Whale (Mesoplodon bowdoini)
Andrew’s Beaked Whale appears to have a circumpolar distribution in the southern hemisphere, however all but 4 of the 35 recorded strandings have been from Australia and New Zealand suggesting this are may form the core of its range. It has been recorded as far south as the Antarctic convergence at Macquarie Island and as far north as Tristan da Cunha in the South Atlantic. It is one of the smaller shorter-beaked mesoplodon species and may be distinctive in its sub-Antarctic range in this respect. Although the adult males show combat scars, they’re only single (not parallel) scars reflecting the fact that the emergent teeth do not reach above the upper jaw. Very little is know of its biology but a calving period of summer-autumn has been inferred from occasional strandings of pregnant females and young calves in New Zealand.
Andrew’s beaked whales are very similar in appearance to Hubb’s beaked whale and are sometimes considered sub-species. Like Hubb’s beaked whale mature males typically have pale to white beaks. They also have a paler dorsal saddle along the back. The
Stejneger’s Beaked Whale (Mesoplodon stejnegeri)
Stejneger’s Beaked whale is restricted to the cold waters of the north Pacific from Japan and California north to Alaska and the Bering Sea. With its essentially sub-arctic distribution it is the North Pacific equivalent of Sowerby’s beaked whale in the North Atlantic, and is probably the dominant beaked whale in its range. This is one of the larger-toothed beaked whales with triangular, forward-oriented, teeth positioned mid-way along the lower jaw on a raised ridge similar to, but not a prominent as, that of Blainville’s beaked whale. As with many mesoplodons it has rarely been seen alive but it is reported to form groups of up to 15 and mass strandings of up to 4 animals have been reported.
They are typically coloured animals – darker above and lighter below, although the pigmentation may vary. A pale collar or shoulder region is seen in some animals with a darker area over the top of the head. In areas where cookie-cutter sharks are found the whales are often covered with the round white scars of their bites. Males are also heavily scarred as a result of fights – raking one another with their large teeth. They have a dark ’flipper pocket’, or depression on the sides of their bodies into which their flippers can rest. The underside of the tail flukes (in some animals at least) have irregular white streaks. Stejneger’s are probably hard to distinguish from Hubb’s beaked whales that share the lower parts of their range, but males the former lack the white beak and cap of the later, while in both sexes the melon is less prominent in Stejneger’s as in the round headed Hubb’s.
Strap-Toothed whale (Mesoplodon layardii)
This is one of the most distinctive beaked whales, with bold black and white markings that almost rival those of the killer whale. Although the contrast between light and dark seems to vary from one individual to another they typical show the reverse of cetacean body markings being dark below and lighter above. A white cape covers the fore part of the animal, from the tip of the beak across the back as far as the dorsal fin, uninterrupted apart from a dark cap across the eyes and forehead. The markings can be clearly visible at sea.
The strap-toothed whale has one of the most unusual sets of teeth of any mammal. As with many beaked whales the teeth only erupt in adult males, but in these individuals they grow up from the lower jaw and around the upper until it is completely encircled and is prevented from opening fully. In fact mature male strap-toothed whales cannot open their jaws more than 11-13cm – not much for an animal up to which can grow to 6m in length. Maladaptive as they seam, these teeth do not appear to lead to starvation, though the diet of this species does appear to be restricted to mainly small fish and squid with an average mantle length of 13-16cm. This is one of a number of species apparently restricted to the southern ocean with most strandings being recorded from New Zealand, South Africa, Australia and South America. Sub-Antarctic prey species have been recorded from whales stranded in South Africa suggesting that some individuals at least are migratory within their Southern Ocean range.
Tasmans Beaked Whale (Tasmacetus shepherdi)
Tasmans Beaked whale is unique among the beaked whales as it has a set of apparently functional (in a feeding capacity) teeth. In total it has 17 – 21 pairs of teeth in the upper-jaw and 17 – 29 in the lower, a similar arrangement to that found in a number of dolphins and porpoises. Although the diet of this species has only been examined from the study of a handful of stranded animals, it has been suggested that this dentition reflects a primarily fish rather than cephalopod (squid) diet. This dentition is also likely to be similar to that of ancestral beaked whales, which are likely to have had a complete set of teeth and only have lost them after the evolution of their unique ‘sucking’ feeding strategy. Like other beaked whales there is one pronounced pair of teeth that protrude from the tip of the lower jaw in mature males. This is a species of the southern oceans with strandings recorded from south Australia, New Zealand, Chile and Argentina.
This is a fairly large species, similar in size to Cuvier’s beaked whale. Overall is profile is similar to that of a bottlenose whale, with a long, pronounced beaked and rounded melon. From descriptions of freshly stranded animals and a few reported sightings at sea it seems to have distinctive pigmentation with a pale forehead and a dark cape that is interrupted by variable pale swaths of colour from the underside – one above the flipper and the other from the dorsal fin across the remainder of the tail stock.
Longman’s Beaked Whale (Indopaceus pacificus)
Until recently this species was only known from two beach-washed skulls one found in Somalia and the other in Queensland, Australia. In recent years, however, a couple of freshly stranded individuals have been discovered and another couple of misidentified specimens recognised. With the discovery of the fresh specimens the field characteristics of this species have become known, confirming that this species has been responsible for a number of sightings of a mystery beaked whale in the southern Pacific. This species is found in the Indian and Southern Pacific Oceans, and has been regularly seen in the waters around the Maldive Islands in recent years, suggesting that this may be a particularly important area for this species.
Bairds Beaked Whale (Berardius bairdii)
This is the largest member of the whale family, longer than a bus and twice the weight of an elephant. Studies of hunted animals hint that these whales may have a complex social structure where male animals play an important role in looking after and nurturing the young.
Restricted to the Northern Pacific ocean, from Japan and California northwards to the Bering Sea, Baird’s beaked whale is possibly the only beaked whale to have been hunted on a regular basis for food. Fisheries for this species once existed off California, British Columbia and Japan, but in recent years it has only been the traditional Japanese coastal fishery that has been active. This appears to be a highly social species with pods of 5 to 20 whales being normal, though pods of up to 50 have been recorded. They appear to be at least partly migratory with sightings over the continental slope being most common in the summer and early autumn. Off Japan there also appears to be a seasonal movement north with peak numbers recorded off the Boso Penninsula (34°N) in August and off Hokkaido (43°N) in October-November before moving to an unknown wintering ground. In inshore waters there also appears to be a bias towards males in the population suggesting that some sexual segregation takes place. As with the other beaked whales this appears to be a deep diving species with most prey species found at depths of 800-1200m. Their diet seems to vary between areas, being squid dominated in some regions and fish dominated in others. However, whether this reflects variations in prey selection or dominant prey availability is unknown. Being deep-divers they are also long divers, with dive times of up to an hour considered normal – significantly longer than they spend at the surface.
True’s Beaked Whale (Mesoplodon mirus)
True’s beaked whale is one of the least known members of the family, only named in 1913 and only reported in a live sighting in 1995. Photographs taken in the Bay of Biscay in 2001 are the first confirmed sighting of this species in European waters.
True’s is a typical beaked whale in form – large and round bodied with a small head and fins. The colour is quite variable but generally a bluish grey with a lighter underside and often a darker eye patch surrounded by lighter skin. The head profile of this species is superficially similar to the bottlenose dolphin, but without the crease separating the melon from the beak. A stranding in South Africa showed a female to have a white tail stock, from the dorsal fin down, its not yet known whether this is a consistent geographical variation.
The distribution of True’s beaked whale is poorly know but is thought to range from Nova Scotia and Ireland to the north and Florida, the Bahamas and the Canaries in the south within the North Atlantic, while in the southern hemisphere strandings have occurred in South Africa and western Australia.
Spade-Toothed Beaked Whale (Mesoplodon traversii)
Mesoplodon traversii is perhaps the least known of all the cetaceans, and ranks as one of the least known mammals in the world. Currently it is only known from three skulls and has never been seen in the flesh. Of the three known specimens two have been found in New Zealand and one on the Juan Fernandez islands, off the coast of Chile, implying that this is a species mainly found in the southern Pacific region. The Juan Fernández specimen was originally described as a new species in 1995 – Mesoplodon bahamodi, but subsequent genetic analysis showed it to be the same species as the New Zealand specimens described a century before, but then forgotten and misidentified until 2002.
Hector’s Beaked Whale (Mesoplodon hectori)
Reaching a maximum length of about 4.2m and weighing around 1 ton, Hector’s is one the smallest of the beaked whales. It’s poorly known from a handful of stranded animals and descriptions have been confused by the fact that animals stranded in southern California were thought to represent this species. Recent work using analyses of DNA has shown these Northern Hemisphere animals represent a new species. Adult males have a pair of flattened, triangular teeth near the tip of the lower jaw. Identifying a young can be difficult but was recently accomplished using DNA scrapped from the skin of an animal swimming close to shore.