Category Sea/Ocean

Do the rougheye rockfish live long?

Yes, they do! In fact the rougheye rockfish are among the longest-lived marine fish species, some of them recorded as old as 205 years. They grow very slowly, and mature late in life.

Does the name of this fish strike you as strange? They really have ‘rough eyes’, because of spines along the lower rim of the eyes. They are also nicknamed ‘blacktip’ rockfish because their pectoral fins have black ends.

The rougheye rockfish live in the Pacific Ocean, from northern Japan and the Bering Sea to southern California. They usually live at depths between 170 to 660 metres, near the seafloor around caves, crevices and boulder fields. They feed mostly on shrimp, but also go for crabs, tiny crustaceans and other fish. The females usually spawn between February and June, releasing larvae from their ovaries. These fish grow to a maximum length of about 97 cm, and their record weight is 6.7 kg.

For most part of the year, the larger fish remain solitary or roam in small groups, but during some periods, the rougheye rockfish form schools.

For most part of the year, these fish remain solitary, but during some periods, the rougheye rockfish roam around in schools (group).

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WHERE WAS THE RARE BABY GHOST SHARK FOUND?

The newly hatched, or neonate, ghost shark was found at a depth of 1200m off the east coast of New Zealand’s South Island. The rare discovery of a juvenile ghost shark off New Zealand’s South Island coast will help researchers better understand the biology and ecology of this mysterious deep water fish.

Ghost sharks or chimaeras are one of the most elusive fish species in the world. They have existed for hundreds of millions of years, but not much is known about them because they usually reside at depths of up to 2,000 metres. The neonate or hatchling was found at a depth of 1,200 metres.

Ghost sharks, also known as ratfish, spook fish or rabbitfish, are not actual sharks but are closely related to sharks and rays. They are cartilaginous, meaning their bodies have stiff armour-like plates and bone-like cartilage. Adult ghost sharks have venomous spines in front of their dorsal fins. Embryos grow inside their egg capsules on the sea floor and feed off the capsules until ready to hatch (between 6 to 12 months).

Critical missing details about the species’ life cycle makes monitoring chimaera populations difficult. Sixteen per cent of all ghost shark species are threatened or near threatened.

Picture Credit : Google 

What makes the sperm whale unique?

Did you know that the invention of the kerosene lamp may have prevented the extinction of the sperm whale? There was a time when these leviathans of the deep were hunted for the white, waxy substance found in their heads, called spermaceti.

People in the 18th century found that this substance could fuel lamps, power streetlights and even light up lighthouses! Consequently the sperm whale was nearly hunted off the face of the globe. It was only the invention of alternative fuel sources like the kerosene lamp that saved these creatures from total annihilation!

The sperm whale is easily recognizable for its prominent block-shaped forehead. It has the largest brain of any animal on earth. It can grow to a length of 60 feet and weigh around 40 metric tons. The female is smaller than the male but eats up to three times more!

Their favourite food is squid, the bigger the better! In fact the giant squid is their favourite snack. To find the giant squid though, the sperm whale has to dive deep into the ocean depths. It is one of the deepest divers of the whale world, capable of 2000-metre dives. This whale can also hold its breath longest of any mammal – 90 minutes! Some scientists think that the spermaceti in the sperm whale’s brain may help them to withstand high pressures on their dives. Their diet also consists of other deep-water prey like sharks, skates and fish.

They are the largest of the toothed whales, but have teeth only on the lower jaw. They have corresponding holes on their toothless upper jaw into which the lower jaw teeth fit into.

Although sperm whales are protected across the world today and spermaceti is no longer used as fuel, they are still hunted for ambergris. This is a substance which forms around squid beaks in a whale’s stomach. It is used in perfumes and is very valuable.

These iconic behemoths are listed under ‘Vulnerable’  in the IUCN Red List.

Picture Credit : Google

How is the bowhead whale special?

The bowhead whale, just as the name suggests, has a bow-shaped head. Just like the Greenland shark, the bowhead whale also lives in the icy-cold waters within the Arctic Circle. Maybe there is a connection between swimming around in the freezing Arctic waters and living very long because both the Greenland shark and the bowhead whale live well beyond 200 years!

The bowhead whale is the fifth largest mammal on earth, growing up to 60 feet and weighing up to 100 tons! The bowhead whale’s head is one-third of its total length. It has baleen plates in its mouth instead of teeth. It eats by swimming with its mouth open and taking in huge amounts of water along with plankton and tiny crustaceans like krill. It then pushes the water out through the baleen plates which act like filters, retaining only the minute plant and animal life. It eats up to 2 tonnes of food in this fashion every day.

Apart from eating, it also uses its enormous head to break through thick layers of sea ice to create breathing holes. Despite its mighty size, this fun-loving whale loves to jump out of the water (a phenomenon called breaching), splash around and sing! It has a repertoire of more than 60 songs and vocalizations. You might say that it likes to have a ‘whale’ of a time!

It is threatened by habitat loss, water pollution and climate change and is listed under ‘Least Concern’ on the IUCN Red List.

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What makes the right whale ‘right’?

Did you know that the right whale is called the right whale for the wrong reasons? This whale was historically considered the ‘right whale’ to hunt as it is composed of 40 percent blubber (whale fat). This fat was traditionally used to make essential items like soap, margarine and oil for lamps.

Today it is the rarest of all large whales found in the ocean. This is so, because from as early as the 10th century onwards, it has been hunted almost to the brink of extinction. Whale hunters targeted these whales for many reasons. For one they are slow – moving at the rate of 8 km/h. They often swim close to the shore and are friendly. They are easy to spot as they have two blowholes and the blow of a right whale is V-shaped, which can be seen miles away. They float after they are killed, instead of sinking like other whales, making it easier for the whalers to harvest their bodies.

This whale grows to 55 feet and weighs as much as 70 tons! It has a very large head (almost one-quarter of its body length) and roughened patches of skin called callosities on the top of its head. It has baleen plates instead of teeth in its mouth, which it uses to filter-feed on its favourite food – zooplankton, crustaceans and krill.

Rampant and unchecked hunting through the centuries led the right whale to the verge of extinction. Fortunately international sanctions were put in place by the 1970s to protect them and this whale species was saved. However, they are still commercially hunted by Japan, Finland and Iceland.

Other than humans the right whale is also hunted by orcas. It is listed as ‘Critically Endangered’ in the IUCN Red List.

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Why is the Greenland shark special?

The Greenland shark seems more suited to the pages of a fantasy novel than real life. It is the longest living vertebrate and the slowest swimming shark in the world. It can live up to 400 years and beyond and reaches maturity only at the age of 150! In fact, some scientists believe that there could be specimens living in the oceans that are 6 centuries old! Imagine a Greenland shark that may have been alive during the time of Christopher Columbus, swimming about today!

This living fossil is also called sleeper shark and swims at a slow and ponderous speed of 1.2 km per hour. Weighing between 400 and 1400 kg, this shark can grow up to 7.31 metres long! It produces more than 700 pups (young ones) during its lifetime.

It is found deep down in the icy cold waters of the Arctic Ocean around the continental shelves of Greenland, Canada and Iceland, at a depth of 2,200 metres. This grey-green, stealthy predator is known to creep up on its prey and swallow it whole. Although apex predators, this shark will eat any flesh dead or alive and are believed to be primarily scavengers by some scientists.

Large proportions of these sharks are affected by parasitic attacks on their eyes and are partially blind. However this does not affect them much, as there is very little light deep down in the oceans and they are used to hunting in complete darkness.

The flesh of the Greenland shark is poisonous. It contains a chemical called Trimethylamine oxide, which can cause intestinal distress and even death if ingested. However, the early settlers in Greenland found a way to prepare the flesh so that it can be eaten safely. They do this by a long process of fermentation and the resultant product, although safe to eat, has been described as very strong smelling and foul tasting by some well-known chefs!

The Greenland shark is listed as ‘Near Threatened’ by the IUCN due to overhunting, parasitic attacks and climate change.

Picture Credit : Google