Whales... an underwater wonder
Whale whale whale, what do we have here?
The largest mammal species on our planet? How cool is that?
These large carnivorous mammals are fully marine and placental i.e. they develop in the uterus during pregnancy. They are warm-blooded mammals and consist of thick blubber/fat under their skin. They have a spindle-shaped body with front limbs modified into flippers which helps them to swim and travel long distances. Although whales are completely aquatic mammals, they have evolved from land-living mammals and hence they need to come to the surface regularly for breathing air and can stay underwater for long periods of time. They have blow-holes which are modified nostrils used for the intake and exhaling of air. 40% of the whale's weight is because of its enormous head.
How long do whales live? It is believed that most large whales (blue whale, humpback whale, fin whale) have a lifespan comparable to a human, and even greater!
The largest mammal species on our planet? How cool is that?
These large carnivorous mammals are fully marine and placental i.e. they develop in the uterus during pregnancy. They are warm-blooded mammals and consist of thick blubber/fat under their skin. They have a spindle-shaped body with front limbs modified into flippers which helps them to swim and travel long distances. Although whales are completely aquatic mammals, they have evolved from land-living mammals and hence they need to come to the surface regularly for breathing air and can stay underwater for long periods of time. They have blow-holes which are modified nostrils used for the intake and exhaling of air. 40% of the whale's weight is because of its enormous head.
How long do whales live? It is believed that most large whales (blue whale, humpback whale, fin whale) have a lifespan comparable to a human, and even greater!
There are two main categories of whales, one of which is baleen whales (odontocetes) which use keratinaceous baleen plates in their mouth for sieving planktonic creatures from water, for example, blue whales and humpbacks. They have an amazing sense of smell. Plates of baleen are fringe-like structures so as for them to intake a huge amount of water retaining krills and plankton.
Did you know that baleen is made out of keratin, the same protein that makes up our fingernails and hair? It is very strong and flexible. They grow downwards from the roof of the whale mouth like multilayered curtains. Baleen plate count, size and colour are different and unique for every whale. They have throat pleats which enable them to expand their mouth and take in a huge quantity of water that consists of billions of krills and plankton.Isn't it extraordinary for blue whales being the largest mammal on this planet to feed on small, micro-foods like plankton and krill?
Baleen-plated whales are usually filter feeders except for Blue whales and Humpbacks, as they are gulpers (they gulp excessive amounts of water in the process of feeding). Bowheads and right whales are skim feeders, as they swim while keeping their mouths half-open. As water enters their mouth, the planktons and krills get trapped in baleen plates. Grey whales swim on their sides along the floor of the ocean bed so as to take in mud and water. They feed on tiny crustaceans from the sludge using baleen plates as a filter for feeding.
Whales are known for creating a great variety of vocalizations, especially the humpback whales. Some baleen whales, including blue and humpback whales also sing complex 'songs' to communicate having a frequency range that is too high or low to be heard by the human ear but can be picked up by specialised acoustic equipment. Think of the large number of musical whales performing shows that must be held down there!
Whales are widespread all over the oceans of the world, though they prefer colder waters. However, they migrate to the equator for warm waters for giving birth to young ones. Whales show sexual dimorphism, with females being larger than males. This is thought to be because their blubber must supply them with enough energy to nurture their calves. Males typically mate with multiple females in one year, however, females only mate every 2 to 3 years. Calves are usually born in spring and summer. Whales become sexually mature at the age of about 6 to 9 years. However, few whales might take longer than that. Humpback males compete with other whales in an aggressive manner in groups called 'heat runs'. After successful mating, female humpbacks give birth to a single calf after a gestation period lasting around 11 months. Calves can weigh about one ton and are 23 feet in length at birth.
Do whales have hair on their body?
All whales have hair on their body at some point in their lives. Whales are born with sensory hair along their jaw and head. Most whales will shed this sensory hair, but some will keep them! (perhaps a beard!)
Whales are widespread all over the oceans of the world, though they prefer colder waters. However, they migrate to the equator for warm waters for giving birth to young ones. Whales show sexual dimorphism, with females being larger than males. This is thought to be because their blubber must supply them with enough energy to nurture their calves. Males typically mate with multiple females in one year, however, females only mate every 2 to 3 years. Calves are usually born in spring and summer. Whales become sexually mature at the age of about 6 to 9 years. However, few whales might take longer than that. Humpback males compete with other whales in an aggressive manner in groups called 'heat runs'. After successful mating, female humpbacks give birth to a single calf after a gestation period lasting around 11 months. Calves can weigh about one ton and are 23 feet in length at birth.
Do whales have hair on their body?
All whales have hair on their body at some point in their lives. Whales are born with sensory hair along their jaw and head. Most whales will shed this sensory hair, but some will keep them! (perhaps a beard!)
Whales sleep by keeping one side of their brain active, alerting them to breathe, while the other half rests. They may sleep at the surface of the water, floating with little movement, a behaviour called logging or they may rest under the surface of the water in a vertical or horizontal position.
Baleen whales:
Blue Whale (Balaenoptera musculus) being 'The largest mammal of our planet' and the gentle Humpback Whale (Megaptera novaeangliae) are a few of the baleen whale examples we might have already heard of before.
Toothed whales:
Belugas, narwhals, porpoises, oceanic dolphins and sperm whales are a few examples of toothed whales.
Their feeding technique? Have you heard of bubble net feeding? BUBBLES! That sounds like fun!
Bubble-net feeding is when whales blow bubbles from their noses to encircle their food (krill and fish) like a net, concentrating their prey into a tight ball. Then, the whale or group of whales swim together from beneath, rise to the surface open their mouths, and gulp up their prey.
Bubble-net feeding is when whales blow bubbles from their noses to encircle their food (krill and fish) like a net, concentrating their prey into a tight ball. Then, the whale or group of whales swim together from beneath, rise to the surface open their mouths, and gulp up their prey.
Baleen whales comparatively are a bit more solitary in nature. The closest association in baleen whales is the bond between a mother and a calf.
Did you know?
Killer whales are actually dolphins. Yes! Killer whales are the largest ones in the dolphin family.
Did you know?
Killer whales are actually dolphins. Yes! Killer whales are the largest ones in the dolphin family.
Are there threats to whales?
Yes! There are a lot of threats faced by whales which has resulted in a huge decline in their numbers and may lead to extinction.
1. Commercial whaling.
Yes! There are a lot of threats faced by whales which has resulted in a huge decline in their numbers and may lead to extinction.
1. Commercial whaling.
It is the practice of hunting and killing whales for the purpose of selling and trading their meat and other products derived from them to critical levels. Some countries with Indigenous or aboriginal populations also continue to hunt whales for subsistence purposes. This practice is called aboriginal subsistence whaling. People around the world have been hunting whales for thousands of years, primarily for their meat and blubber. Whalebone was used to make corsets, hat brims, umbrella ribs, riding crops, and buggy whips.
2. Pollution.
Plastic being one of the major contributors to pollution, is often mistaken by these creatures as food and ingested, causing fatal blockages in their digestive system as well as the respiratory system which is even worse for the health of pregnant female whales and their infants yet to be born. Not just plastic but discarded net traps in the ocean waters are a death trap for them. Many whales get entrapped in these and are brought to the shallow waters by strong water currents, and eventually, end up on shores and die. Many toxins discarded into the ocean waters make their way into plankton and hence disturb the whole food chain. These toxins are found by scientists and conservationists in the skin and blubber/fat of whales. Oil spills, not only caused by ship wreckages but also due to leakage during transportation, drilling lubricants used by the oil industry can contain high concentrations of hydrocarbons and heavy metals causing a lot of disturbance to marine life. Hydrocarbons, including crude oil, can be released intentionally by oil tankers after offloading, or unintentionally through accidental discharges and oil spills.
3. Toxic algal blooms.
These occur naturally but they are also thought to be stimulated by factors such as pollution, population growth, changing weather patterns and dredging of the ocean floor. Many `red tide' algae produce phytotoxins hazardous to marine life.
4. Attack on whales due to fear and unawareness is also one of the leading reasons for such decline in their numbers.
2. Pollution.
Plastic being one of the major contributors to pollution, is often mistaken by these creatures as food and ingested, causing fatal blockages in their digestive system as well as the respiratory system which is even worse for the health of pregnant female whales and their infants yet to be born. Not just plastic but discarded net traps in the ocean waters are a death trap for them. Many whales get entrapped in these and are brought to the shallow waters by strong water currents, and eventually, end up on shores and die. Many toxins discarded into the ocean waters make their way into plankton and hence disturb the whole food chain. These toxins are found by scientists and conservationists in the skin and blubber/fat of whales. Oil spills, not only caused by ship wreckages but also due to leakage during transportation, drilling lubricants used by the oil industry can contain high concentrations of hydrocarbons and heavy metals causing a lot of disturbance to marine life. Hydrocarbons, including crude oil, can be released intentionally by oil tankers after offloading, or unintentionally through accidental discharges and oil spills.
3. Toxic algal blooms.
These occur naturally but they are also thought to be stimulated by factors such as pollution, population growth, changing weather patterns and dredging of the ocean floor. Many `red tide' algae produce phytotoxins hazardous to marine life.
4. Attack on whales due to fear and unawareness is also one of the leading reasons for such decline in their numbers.
~Vidhi Lahoti
Image sources:
https://www.sealifer3.org
https://www.worldwildlife.org
https://en.wikipedia.org
https://www.thoughtco.com
https://www.discoverwildlife.com
https://www.veniceoceanarium.org
https://www.smithsonianmag.com
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