#euphausiacea

(Sources - 1, 2, 3, 4)

Order: Euphausiacea

Common Name: “krill”

Families: 2 - Euphausiidae and Bentheuphausiidae

Anatomy: decapod-like body with a cephalothorax, segmented abdomen, and tail fan (telson); two antennae; leg number varies among species but all have five pairs of swimming legs in addition to a number of feeding and grooming legs; most species have a transparent exoskeleton; most species are bioluminescent

Diet: phytoplankton, zooplankton

Habitat: in oceans worldwide; undergo a diurnal vertical migration: spending the day in the deep sea and rising to shallower waters at night

Evolved in: Devonian

Propaganda under the cut:

Euphausiacea. This order is made up of krill, small marine crustaceans. Most species form large swarms, and they are important for the marine food chain.

Isopoda. This order is made up of isopods, including terrestrial species like the potato bug and aquatic species like the giant isopod. Some eat dead matter, others are filter feeders, and some are parasites, mostly of fish.

Cambiamenti climatici e “ghiacciai bollenti”: 40% in meno per quegli alpini in 50 anni

Artide, Antartide Alpi, Himalaya, Patagonia, Alaska, questo solo alcuni dei “santuari del ghiaccio” nei quali è collocato quel 40% del nostro pianeta ricoperto da ghiacci e manto nevoso, fondamentale sistema di raffreddamento che si va gradualmente deteriorando a causa del riscaldamento globale. A fornirci una visione planetaria sul fenomeno della riduzione dei ghiacci del pianeta e dei suoi…

HAVE YOU TAKEN THE KRILL QUIZ? HOW MUCH DO YOU KNOW ABOUT THE ANTARCTIC KRILL?

Take this short quiz and evaluate your knowledge

Created by the Antarctic Ocean Alliance, the online test sees how much we know of krill. It is short, entertaining and very educational. How many points you got

(Source/source/source)

Krill are small crustaceans of the order Euphausiacea, and are found in all the world's oceans. The name krill comes from the Norwegian word krill, meaning "young fry of fish", which is also often attributed to other species of fish.  Currently, 85 species of krill have been identified in different oceans around the world. They live in habitats ranging from abyssal depths (5,000 m) to near shore kelp beds (10 m), and from warm tropical seas to the freezing Antarctic Ocean. Most marine species in the Southern Ocean – including whales, seals, penguins, albatrosses, petrels, squid and many others – feed on this small shrimp-like organism, making them an extremely important part of the ecosystem.  

Krill are crustaceans and have a chitinous exoskeleton made up of three tagmata: the cephalon (head), the pereion (fused to the cephalon to form a cephalothorax), and thepleon. This outer shell of krill is transparent in most species. Krill feature intricate compound eyes; some species adapt to different lighting conditions through the use of screening pigments. They have two antennae and several pairs of thoracic legs called pereiopods or thoracopods. These thoracic legs include feeding legs and grooming legs. Additionally all species have five pairs of swimming legs calledpleopods or "swimmerets", very similar to those of a lobster or freshwater crayfish. Most krill are about 1–2 centimetres (0.4–0.8 in) long as adults; a few species grow to sizes on the order of 6–15 centimetres (2.4–5.9 in). 

Krill are considered an important trophic level connection – near the bottom of the food chain – because they feed on phytoplankton and to a lesser extent zooplankton, converting these into a form suitable for many larger animals for whom krill makes up the largest part of their diet. In the Southern Ocean, one species, the Antarctic krill, Euphausia superba, makes up an estimated biomass of around 379,000,000 tonnes, more than that of humans. Antarctic krill is the keystone species of the Antarctica ecosystem, and provides an important food source for whales, seals, Leopard Seals, fur seals, Crabeater Seals, squid,icefish, penguins, albatrosses and many other species of birds.   A possible decline in Antarctic krill biomass may have been caused by the reduction of the pack ice zone due to global warming.Antarctic krill, especially in the early stages of development, seem to need the pack ice structures in order to have a fair chance of survival. The pack ice provides natural cave-like features which the krill uses to evade their predators. Another challenge for Antarctic krill, as well as many calcifying organisms (corals, bivalve mussels, snails etc.), is the Acidification of the oceans caused by increasing levels of carbon dioxide. Krill exoskeleton contains carbonate, which is susceptible to dissolution under low pH conditions. It has already been shown that increased carbon dioxide can disrupt the development of krill eggs and even prevent the juvenile krill from hatching

Krill; Euphausiacea; San Lucas, Baja, CA; Collected by M.H.N

"We think of krill as that single pink cloud that moves in balletic undulations across the ocean in nature documentaries, sustenance for some of the largest inhabitants of this earth—baleen whales. But seeing each tiny droplet, with its two black pinprick eyes, lifeless and immobile in a specimen jar, is a very different way to view this keystone species. In an operation inverse but equal to the hi-res images that reveal the billions of stars that make up the Milky Way, it reminds us that 'amorphous' and 'anonymous' are only a matter of perspective (as are their opposites), and that even the tiniest of creatures can make us feel small."

Thysanoessa raschii

Sometimes known as the "Arctic Krill" Thysanoessa raschii is a species of Krill (Euphausiacea) that is common in subarctic and Arctic seas. Like other krill T. raschii is a filter feeder and will filter the water around it for phytoplankton and diatoms. T. raschii is an important food item for a wide range of a large number of marine animals, including marine mammals, seabirds, and planktivorous fish. 

Classification

Animalia-Arthropoda-Crustacea-Malacostraca-Euphausiacea-Euphausiidae-Thysaenoessa-T. raschii