Скачать или смотреть Krill (Order Euphausiacea)

▪︎ (Order Euphausiacea) Krill are small & exclusively marine crustaceans found in all the world's oceans.

Name 'krill' comes from Norwegian word krill, meaning 'small fry of fish' which is also often attributed to species of fish.

Krill are considered an important trophic level connection near bottom of food chain. They feed on phytoplankton & to a lesser extent zooplankton & are also main source of food for many larger animals.

In Southern Ocean, one species, Antarctic Krill, makes up an estimated biomass of around 3.79 billion tonnes, making it among species with the largest total biomass. Over half of this biomass is eaten by Whales, Seals, Penguins, Seabirds, Squid, & Fish each year. Krill are also main prey of Baleen Whales, including Blue Whale.

Most Krill species display large daily vertical migrations thus providing food for predators near surface at night & in deeper waters during day.

Most of Krill catch is used for aquaculture & aquarium feeds, as bait in sport fishing, or in pharmaceutical industry. In Japan, Philippines & Russia, krill are also used for human consumption.

Krill are Crustaceans they have a 'chitinous exoskeleton'. They have anatomy similar to a standard Decapod with their bodies made up of three parts -
¹cephalothorax is composed of head & thorax which are fused
²abdomen which bears ten swimming appendages
³tail fan.
This outer shell of krill is transparent in most species.

Krill feature intricate compound eyes. Some species adapt to different lighting conditions through use of screening pigments.

They have 2 antennae & several pairs of thoracic legs called pereiopods or thoracopods, so named because they are attached to thorax. Their number varies among genera & species. These thoracic legs include feeding legs & grooming legs.

Krill are probably sister clade of Decapods because all species have five pairs of swimming legs called 'swimmerets' in common with latter, very similar to those of a lobster or freshwater crayfish.

In spite of having ten swimmerets, otherwise known as pleopods, krill cannot be considered decapods. They lack any true ground-based legs due to all their pereiopods having been converted into grooming & auxiliary feeding legs. In Decapoda, there are ten functioning pereiopods, giving them their name; whereas here there are no remaining locomotive pereiopods. Nor are there consistently ten pereiopods at all.

Most krill are about 1-2 cm. long as adults. A few species grow to sizes on order of 6-15 cm. Largest krill species (Thysanopoda spinicaudata) lives deep in open ocean. Krill can be easily distinguished from other crustaceans such as true shrimp by their externally visible gills.

Except for (Bentheuphausia amblyops), krill are bioluminescent animals having organs called photophores that can emit light.
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♡ Kingdom Animalia (114102)
♧³ Phylum Arthropoda (1203181) - Arthropods
♤ Class Arachnida - Spiders, Scorpions, Ticks, Mites, Pseudoscorpions, Harvestmen, Camel Spiders, Whip Spiders, Vinegaroons.
♤ Class Branchiopoda - Fairy Shrimp, Clam Shrimp, Water Fleas, Shield Shrimp
♤ Class Cephalocarida - Horseshoe Shrimp
♤ Class Chilopoda - Centipedes
♤ Class Collembola - Springtail
♤ Class Copepoda - Copepod
♤ Class Diplopoda - Millipedes
♤ Class Diplura - Two-Pronged Bristletails
♤ Class Insecta - Insects
♤ Class Malacostraca (45953) - Malacostracans - Crabs, Lobsters, Crayfish, Shrimp, Krill, Prawns, Woodlice, Amphipods, Mantis Shrimp, Tongue-Eating Lice
☆¹ Order Amphipoda (10590) - Shrimp-like in form
☆² Order Anaspidacea
☆³ Order Bathynellacea
☆⁴ Order Bochusacea
☆⁵ Order Cumacea - Hooded Shrimp, Comma Shrimp
☆⁶ Order Decapoda (19652) - Decapods
☆⁷ Order Euphausiacea (88) - Krill
• Family Bentheuphausiidae
• Family Euphausiidae
☆⁸ Order Isopoda (11025) - Woodlice
☆⁹ Order Leptostraca
☆¹⁰ Order Lophogastrida - Shrimp-like Animals (deep pelagic waters)
☆¹¹ Order Mysida - Opossum Shrimps
☆¹² Order Stomatopoda - Mantis Shrimp
☆¹³ Order Tanaidacea - Tanaids
☆¹⁴ Order Thermosbaenacea - Crustaceans that live in thermal springs in fresh water, brackish water & anchialine habitats
♤ Class Maxillopoda - Barnacles, Copepods
♤ Class Merostomata - Horseshoe Crabs
♤ Class Ostracoda - Seed Shrimp
♤ Class Pauropoda - Millipede-like Arthropods
♤ Class Protura - Coneheads
♤ Class Pycnogonida - Sea Spider
♤ Class Remipedia - Blind Crustaceans
♤ Class Symphyla - Garden Centipedes, Pseudocentipedes
♤ Class Tantulocarida - Parasitic Crustaceans
♤ Class †Trilobita - Trilobites
♤ Class Not assigned
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