Beluga Whale / White Whale - Facts and Adaptations
Delphinapterus leucas

The only all white whales, belugas are small and highly social, living in fluid travelling groups that can become quite large at certain times of the year. They have a variety of facial expressions and can be musically vocal earning them the name of "canary of the sea".

Distribution range of the beluga whale

  What are Belugas like? how do they survive?

Belugas are striking looking toothed small whales, they have the ability to move their heads independently of their body unlike other whales which along with the ability to move their face into a variety of expressions makes them seem more human and relatable than many other marine mammals. There is a bump at the front of the head called the melon which is involved in making and projecting sounds and in echolocation.

Belugas like company and form groups called pods of around 10 individuals on average with a range of 2 to 25, though during the summer months they can form groups of hundreds or thousands in shallow waters such as estuaries and coastal areas. Different groups behave differently in terms of being migratory depending on where they live, some will travel over large distances from summer to winter whereas others do not migrate far at all. The smaller groups may have related members, though they are quite fluid and individuals may join or leave one group for another on a fairly regular basis, generally males will travel together in a group while females with their offspring form their own groups.

Like many social animals, belugas are enthusiastic vocal communicators making a variety of sounds from whistles and chirps  to clicks, clangs and squeals that can sometimes be heard above the water even when on a small boat. They are able to imitate sounds they hear around them including human speech.

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Beluga Whale Adaptations:

Beluga whales have a set of particular anatomical, behavioural and physiological adaptations that allow them to survive successfully.

• Extensive range of vocalizations (anatomical and behavioural) - Belugas have the anatomical structures to be able to make a wide range of vocal sounds, unlike humans with our vocal cords, belugas produce these sounds  in the nasal sacs near the blowhole but like humans some of them can be modified by the shape of the lips under the control of a series of small muscles. There is a variety of reasons for these sounds, communicating with other whales in the pod and in the vicinity is important, but they are also used for echolocation. The melon at the front of the head focuses a series of clicks into a beam projecting forwards from the whale where they bounce off objects, the echoes being interpreted by the whale. In this manner whales can find their way about in water and also find holes in sea-ice for breathing or even pockets of trapped air under the ice that can also be used.
  
  The sounds made by different populations of belugas are more different the further away the animals live, so beluga populations have accents in a similar way to identified amongst other animals such as birds.
  
  
• No dorsal fin, but an elongated dorsal ridge (anatomical) - Most whales have a dorsal fin (in the middle of the back) which helps them maintain a steady line when swimming, belugas don't have this fin, but instead have a hardened long dorsal ridge. The lack of fin is an adaptation to swimming under sea-ice when it might get caught or damaged, the ridge performs a similar job and is also used with the head for pushing up against ice to break through.
  
  
• Live in groups of various sizes (behavioural) - Belugas spend their lives living in groups, typically of about 10 individuals, generally between 2 and 25 and sometimes up to hundreds or even thousands, there are a number of advantages to group living. Groups of any size help them avoid predators by confusing the predators when they attack so making a kill less likely and by providing more animals that may spot and alert the group to those predators sooner rather than later.
  
  Co-operative hunting, belugas generally live in shallow coastal waters feeding at depths of 20m (66ft) and less, several animals can herd prey into a tighter area where they can be more successfully isolated and attacked.
  
  Keeping open breathing holes or polynyas. If belugas don't move south soon enough in the winter, they may be trapped by sea ice. Their constant movement and surfacing can help to keep these holes open for longer than if the water was calm, this is more readily accomplished with many whales, so working together in this way they have a better chance of survival than they would alone.
  
  
• Low surface area to volume ratio (anatomical) - Like all marine mammals that live in icy waters, belugas are large animals, even though they are relatively small for whales and large size makes it easier to stay warm by retaining metabolic heat, belugas have a clean shape with only the flippers adding much extra surface area.
  
  
• Countercurrent heat exchanger in the flippers and flukes ((anatomical and physiological) - Arteries in the flippers and flukes taking blood in are surrounded with veins taking blood out, so that warm blood entering is cooled down by the cold blood leaving. In this way warmth is retained rather than being lost because of the high surface area - low volume of the flipper. In other circumstances blood flow to the flippers can be increased allowing the flippers to be used to cool the body after exertion and/or in warmer waters.
  
  
• Thick blubber layer under the skin for insulation ((anatomical and physiological) - Blubber or fat is an excellent source of insulation, it also provides a means of storing food when times are good and there is plenty to eat as well as providing buoyancy and streamlining. Belugas live in cold waters all year round, any mammal other than whales or seals would eventually get too cold and die of hypothermia in the conditions they live in whereas belugas are able to maintain a constant warm mammalian body temperature at temperatures down to the freezing point of water thanks to their blubber which can make up 40% of a belugas mass.

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Belugas in an aquarium

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• Diving physiology (physiological and anatomical) - While belugas aren't champion divers in the world of whales, they are still capable of impressive underwater dives that require very specialist adaptations. Typically they dive to about 20m (66ft) though the deepest recorded is 647m (2,123ft), they usually stay underwater for less than 10 minutes, but have been measured at more than 17.
  
  
  • Collapsing the lungs when diving with only the minimum of air held in the respiratory system. This prevents any retained air (or more specifically the nitrogen in that air) from being forced into the blood under pressure at depth and coming out again on resurfacing so resulting in the "bends" which can be damaging or even fatal.
    
    
  • Bradycardia, the slowing down of the heart considerably from the normal rate. The heart rate slows to 12-20 beats a minute during a dive, blood is directed only towards the vital organs such as the brain and heart and to the swimming muscles and those associated with catching prey. The rest of the body is largely bypassed for the duration of the dive to retain oxygen for immediately necessary purposes only.
    
    
  • Proportionally more blood than a land mammal. More blood means more oxygen storage capacity that will be available during a dive.
    
    
  • Large amounts of myoglobin in the swimming muscles to store oxygen for use during a dive. Myoglobin is a large protein molecule similar to haemoglobin that carries oxygen in the blood. Haemoglobin gives up its oxygen before myoglobin does, so once the haemoglobin source of oxygen is exhausted, then myoglobin gives up its oxygen to the muscles enabling them to work efficiently for longer. large amounts of myoglobin in diving animals makes their muscle a deep red colour.
    
    
  • Oxygen loading and ridding of carbon dioxide before a deep and long dive. Long deep breaths are taken while at rest before diving to clear dissolved CO2 from the blood and load up haemoglobin and myoglobin with oxygen before the dive to enable a longer period before the next breath.
    
    
• Smooth streamlined shape to enable easy movement through the water (anatomical) - The tail flippers are held separately from the body (as in many aquatic animals) which means that the tail can act as a unique entity for generating thrust away from the body which has its own hydrodynamic shape. The tail is connected to the body by a narrow region only to allow this.
  
  
• Nostrils on top of the head forming a blow hole (anatomical) - In common with other Cetaceans belugas have a blow-hole on top of the head making breathing easier when swimming and surfacing
  
  

Beluga whale video 2 mins 23 secs

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Picture credits and licences: Head in basic facts box - Steve Snodgrass, CC2 Attribution Generic / Distribution map - Pcb21, Gnu 1.2 free document / Group of whales - Ansgar Walk1, CC3 Attribution Share Alike Unported / Two whales in aquarium - Diliff, CC2.5 Attribution Share Alike Generic