Blobfish: Adaptation as a Deep Sea Fish & More

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Blobfish, Psychrolutes marcidus, is a deep-sea fish that live on the ocean floor. The natural habitat of the blobfish is in the deep sea off the coast of Australia and Tasmania. They live in depths of 600–1200 meters underwater.

Structural and Behavioral Adaptations

The gelatinous body of the blobfish is characterized by a large head that tapers back into a small flat tail. The size of an adult blobfish is approximately 30 cm in length. Many of the blobfish’s unique features are due to its adaptation to their specialized habitat. Residing in deep depths of the sea, they must survive in an environment where the water pressure is up to 80 times higher than normal sea level.

NOAA/MBARI, Public domain, via Wikimedia Commons

In such conditions, bones of normal creatures would be crushed and swim bladders would prove inefficient. A swim bladder is a gas filled sac that is present in most fish that live close to the water surface. It allows these fish to control its buoyancy. When the sac is filled with air, the fish will float to the surface. If blobfish had a swim bladder, it would immediately implode under pressure. Thus, they have adapted with a body structure consisting of mainly gelatinous mass and relative lack of muscle. Their entire body is only slightly denser than water. This adaptive body structure allows them to float in the depths of the sea with very little energy expenditure.

Food and Diet

What does the blobfish eat? As a predator of the deep sea, blobfish prey on other invertebrates by ambush and foraging. Their diet includes sea crabs, sea urchins, shellfish and mollusks. It is believed that they sit very still on the ocean floor and wait for prey such as shrimp and other invertebrates to pass by. When they do, the blobfish would gulp them up. Since blobfish do not have teeth, the prey would be swallowed whole. Such ambush-style hunting strategy is one of their behavioral adaptation to their environment. If the blobfish was to pursuit the prey on a chase, it would consume too much of their precious energy. In addition, they would not be a good chaser anyways since they are not fast swimmers.

There are no known natural predators of blobfish. However, due to fishing practices such as ocean bottom trawling, than can get caught in the nets as bycatch.

Kerryn Parkinson © NORFANZ Founding Parties

The image shows the blobfish out of water. The blobfish are adapted to living in the deep sea where the water pressure is very high. Their gelatinous body is a result of evolution and their way of surviving in an otherwise deadly environment. Therefore, when the blobfish is brought out of the water, it is unable to adjust to the vastly different atmospheric pressure, resulting in a blob-like appearance.

Blobfish Reproduction

Blobfish reproduction was first recorded in 2000 on the Gorda Escarpment near the coast of California. The reproductive activity consisted of groups of nests with approximately 100,000 eggs each. These nests of eggs were located on deep sea plateaus, in rocky areas. These pink colored eggs in the nest were tended by brooding blobfish. This is most likely when they are the most vulnerable to other animals.

Producing large batches of eggs at once, and doing this collectively as a group, may appear to be a risky survival strategy. However, one can argue that this is another behavioral adaptation to their environment, which requires them to be efficient in their energy expenditure.

Understanding Blobfish

Since the blobfish lives so deep in the ocean, it is difficult to study them and get a full understanding of them. A lot of what we currently know about the blobfish is from the dead ones that are captured as bycatch in fishing nets.

Unfortunately, the exact population of blobfish is unknown as well. Some experts do believe that the population is endangered by deep-sea fishing and bottom trawling in their habitat. Although blobfish are not edible, they are still being caught and dragged up with other marketable fish and invertebrates.

Scientists estimate that blobfish has a life expectancy of approximately 130 years. These estimates are based on the life expectancy of other related deep sea fish.

There is much to learn about the blobfish.