Krill: A Day in the Life of the Crustaceans

Krill are marine crustaceans that look similar to shrimp, and they are of the order of Euphausiacea. Krill are tiny invertebrates that inhabit oceans all across the world. If krill want to be capable of surviving, they have to grow, eat, reproduce and defend themselves. Krill usually live in very deep waters that range from 330 feet to as much as 13,000 feet beneath the ocean’s surface, which makes their living environment very, very dark and murky.

What and How Krill Eat:

Krill eat by filtering their food out of the water, utilizing their thoracic legs as if they were baskets. The water is filtered through the basket, leaving behind the plankton that the krill look for as food. Krill then employ their other legs to transfer the food (plankton) to their mouth. The food that krill mostly feed on are two kinds of plankton: zooplankton and phytoplankton. Zooplankton is detritivorous and heterotrophic plankton that drift in seas, oceans and even other bodies of fresh water. Phytoplankton are known as the autotrophic portion of the plankton community.

How Krill Grow:

Krill are able to grow in a particular manner. They either shed, or they molt their skeletons. Krill are known to grow and molt throughout their natural lives, and their bodies end up shrinking each and every time that they do molt, provided that the food is scarce. These tinier bodies need only less food or energy to maintain.

In krill, the phenomenon of molting happens every time that they outgrow their external skeleton that is already in existence. Younger krill—due to the fact that they actually grow faster than bigger and older krill—will molt many more times than older krill. The number of times that krill molts depends greatly on the specific species of krill, and the number of times that krill molts can also be subject to a host of external factors like foods’ availability, the temperature of the water, and the latitude. Krill larvae are known to molt as much as once every four days, while adults are known to molt about once in every six days.

Self Defense

18 different species of krill are known to create great, shapeless swarms that can, at times, get to be the length of many city blocks. Normally, said swarms spend their day at lower depths for the purpose of eluding other animals who want to kill and eat them. A lot of mammals, sea birds and fish, too, prey on krill. These krill move to the ocean’s surface in order to feed, and krill are also able to utilize their swimmerets to propel themselves for distances that are short, yet they use currents in the ocean to move over larger distances. Krill are equipped with the capability of adjusting their bodies’ buoyancy so that they are able to both sink and rise to various levels in any body of water. If krill are or feel threatened, they are able to immediately molt, which leaves behind an external skeleton that is empty and acts as a decoy.

Krill Reproduction

By employing a deep-sea video camera, some scientists who work at the Australian Antarctic Division (AAD) discovered that the Antarctic krill in particular has the capacity to breed deeper in the ocean than what was once believed by researchers. Said footage exposed some stunning aspects of the hidden lives of krill. Although krill were only thought to both live and breed in the upper portions of water, they are known to now live in much deeper portions of the ocean. To satisfy their study, these scientists launched their camera 400 meters to 700 meters at 16 different positions off of East-Antarctica. 14 of these locations revealed krill at high densities. Prior ideas on the life cycles of krill have been challenged as a direct result of this study by the Australian Antarctic Division, and this will have the effect of intensifying the comprehension of the marine ecosystem of the Antarctic.

Krill are abundant in many oceans all across the world, and they are an essential part of the food chain and, thus, the ecosystems of the ocean. Krill eat different kinds of plankton, and they are known to molt many times over the course of their lives. Krill are mysterious creatures that inhabit the deeper parts of the oceans across the world, which is why not much is known about their reproduction. This changed, however, when scientists found out that they in fact occupy deeper sections of the oceans.

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