One of the most essential criteria for survival of a living organism is food. However, evolution has made some creatures like the ‘deep sea fishes’ to undergo severe hardships in their life. One of which is lack of light. Light does not penetrate in the depths of the sea. That means the bottommost point encompasses complete darkness. And ‘darkness’ makes obtaining enough food a difficult task for its inhabitants. Predators in the deep sea must be either very efficient or should be capable of enduring for long periods without food. Read on to know the extra-ordinary adaptations of deep sea fishes against harsh darkness and scarcity of food.
Let there be light-
Some deep sea animals have the ability to create light by their light emitting organs which involves a chemical reaction- bioluminescence. They flash impressive light that will surely rival the streets of Las Vegas. Fishes like firefly squids, hatchet fish, and brittle stars, sea cucumber, and viper fish are some of the deep sea fishes that can help feed themselves with this kind of illumination.
- Firefly squids- They use their light to attract their prey. By on and off flashing, they lure small fishes and pounce on them with their mighty tentacles.
- Hatchet Fishes-They have large tubular eyes that enable them to search for food. Their eyes are extremely sensitive to light and have an extra-ordinary capability to distinguish shadows in an extreme faint illumination.
- Brittle stars- They feed on decaying matter, detritus, planktons, oysters, small clams and so on. They wrap themselves around the prey and feed on their mucus. They do not have a large mouth or esophagus. The food is ingested directly into their stomachs. They use their stomachs to grab food, digest the food and later excrete it through their mouth itself. They produce light through their green or blue wavelengths. This light is mostly a detector for predators.
- Viperfishes-They keep flashing their light on and off which draws prey closer to it. The light emitting photophores are located on the dorsal fin ray as well as on its sides that helps it camouflage itself from below. Their extra-large stomachs are used to store food when it is abundant. They can live for days without food.
The Roving Eyes-
Many deep sea fishes have relatively larger eyes than their counterparts for catching their prey and avoiding predators. Large eyes help them to collect light as much as possible in the perpetual darkness. Lanternfishes are one of those gifted species that have the ability to focus and channel in whatever little light they get.
The flashing sequence of these organs is dictated by its hormonal control since photophores are connected to its nervous system. Some species of lanterfishes consist of light organs on their tails to entice potential predators. During the night they migrate to the surface to feed and descend back to the depths during the day. By doing this, they also save themselves by the risk of predation from the larger species.
They make ‘sense’-
Many other deep sea fishes are visionless. Therefore, they depend on other senses including smell, touch or taste in the quest of understanding their environment. Some deep sea fishes also have rare capabilities like ‘lateral lines’, a sense organ that helps in detecting the movements and vibrations in the sea. Their longs fins can also work great for them. Angler Fishes are one of them.
‘Lateral line systems’ are a tangible sense organ that is unique to aquatic vertebrates that helps a fish to detect movements in the surrounding water. They appear on the skin and are embedded in the mucus-filled structure called ‘lateral line canals’. The line runs along the body sides starting from the head and dividing itself into snout and lower jaws.
‘Echolocation’ is another extra-ordinary peculiarity present in many deep sea animals. It is calling out to the environment and listening to the echoes of calls that return from different objects near them. This process helps them to identify and locate the objects. It helps them in navigating their prey underwater where there vision is limited. This special acoustic characteristic exists in dolphins, whales and porpoises.
The Strong Stomachs-
Other fishes live on by having large mouths, expandable stomachs and hinged jaws to process large quantities of food that is scarce. Black Swallowers are one such deep sea creatures that survive by feasting on other fishes that can be up to four times their size.
- Other small fishes feast on other dead creatures or carcass that fall from above.
- Food is really hard to find deep down under, that’s the reason they do not eat everyday like us. They can go a couple of weeks without food.
- They do not actively hunt for food since it takes a lot of energy (that they can’t afford to waste)
- As soon as deep sea creatures have eaten something, it takes a long time for them to digest its meal. That’s the reason its food supply can last longer.
Through marine life, nature wants to convey us, that no matter how much ever life pressures us with its atrocities, still life has to go on. Some create ways for themselves, while others just wait for the right chance, so much like human beings, don’t you think?