| Kowalevskia | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Subphylum: | Tunicata |
| Class: | Appendicularia |
| Order: | Copelata |
| Family: | Kowalevskiidae Lahille, 1888 |
| Genus: | Kowalevskia Fol, 1872 |
| Synonyms | |
| |
Kowalevskia is a genus of larvacean tunicates, the only one in the family Kowalevskiidae. [1]
Kowalevskia is a small larvacean. In the adult, the body measures around 1 mm long, while the tail is 8 mm long, appearing stretched and tapered at its ends. [2] [3]
Unlike other Appendicularia species, Kowalevskia doesn't have a heart. Instead, the circulatory system is powered by the beating tail. [2]
Kowalevskia also lacks an endostyle, being replaced by a ciliated groove without glandular cells. [4] [5]
The spiracles also differ from other families, being shaped as long, narrow slits. [4]
Uniquely among larvaceans, Kowalevskia's house is ellipsoidal or toroidal in shape, 1 to 2 cm in diameter. It has a single opening, acting both as inlet and outlet. [3]
Both species of Kowalevskia have a wide distribution. K. tenuis can be found in the East Atlantic and West Pacific, as well as in the Mediterranean and Black Seas. Meanwhile, K. oceanica is found in the Mediterranean and North-East Atlantic, as well as in the Red Sea and West Indian Ocean. [3]
The monotypic Kowalevskiidae is believed to be the sister taxon to Fritillariidae, with both sharing specialized characteristics and forming a clade to the exclusion of Oikopleuridae. [4]
The white-tailed eagle, sometimes known as the 'sea eagle', is a very large bird of prey, widely distributed across temperate Eurasia. Like all eagles, it is a member of the family Accipitridae which includes other diurnal raptors such as hawks, kites, and harriers. One of up to eleven members in the genus Haliaeetus, which are commonly called sea eagles, it is also referred to as the white-tailed sea-eagle. Sometimes, it is known as the ern or erne, gray sea eagle and Eurasian sea eagle.
A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata. It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords. The subphylum was at one time called Urochordata, and the term urochordates is still sometimes used for these animals. They are the only chordates that have lost their myomeric segmentation, with the possible exception of the 'seriation of the gill slits'. However, doliolids still display segmentation of the muscle bands.
Larvaceans or appendicularians, class Appendicularia, are solitary, free-swimming tunicates found throughout the world's oceans. Like most tunicates, larvaceans are filter feeders. Unlike most other tunicates, they keep their tadpole-like shape as adults, with the notochord running through the tail. They can be found in the pelagic zone, specifically in the photic zone, or sometimes deeper. They are transparent planktonic animals, usually ranging from 2 mm (0.079 in) to 8 mm (0.31 in) in body length including the tail, although giant larvaceans can reach up to 10 cm (3.9 in) in length.
The Atlantic horse mackerel, also known as the European horse mackerel or common scad, is a species of jack mackerel in the family Carangidae, which includes the jacks, pompanos and trevallies. It is found in the eastern Atlantic Ocean off Europe and Africa and into the south-eastern Indian Ocean. It is an important species in commercial fisheries and is listed as a Vulnerable species on The IUCN Red List of Threatened Species.
The serpent eel or sand snake-eel is an eel found in the eastern Atlantic Ocean, western Mediterranean Sea, western Indian Ocean, western Pacific Ocean and the north-east and west coast of North Island in New Zealand. It is an elongated, slender fish with a length of up to 250 centimetres. It spends the day with its body immersed in the sediment, emerging into the open water at night.
The Portuguese dogfish or Portuguese shark, is a species of sleeper shark of the family Somniosidae. This globally distributed species has been reported down to a depth of 3,675 m (12,057 ft), making it the deepest-living shark known. It inhabits lower continental slopes and abyssal plains, usually staying near the bottom. Stocky and dark brown in color, the Portuguese dogfish can be distinguished from similar-looking species by the small spines in front of its dorsal fins. Its dermal denticles are also unusual, resembling the scales of a bony fish. This species typically reaches 0.9–1 m (3.0–3.3 ft) in length; sharks in the Mediterranean Sea are much smaller and have distinct depth and food preferences.
The velvet belly lanternshark is a species of dogfish shark in the family Etmopteridae. One of the most common deepwater sharks in the northeastern Atlantic Ocean, the velvet belly is found from Iceland and Norway to Gabon and South Africa at a depth of 20–2,490 m (66–8,169 ft). A small shark generally no more than 45 cm (18 in) long, the velvet belly is so named because its black underside is abruptly distinct from the brown coloration on the rest of its body. The body of this species is fairly stout, with a moderately long snout and tail, and very small gill slits. Like other lanternsharks, the velvet belly is bioluminescent, with light-emitting photophores forming a species-specific pattern over its flanks and abdomen. The ventral photophores are thought to function in counter-illumination, which camouflages the shark against predators and prey. The bioluminescent flank markings may play a role in intraspecific communication.
The European anchovy is a forage fish somewhat related to the herring. It is a type of anchovy; anchovies are placed in the family Engraulidae. It lives off the coasts of Europe and Africa, including in the Mediterranean Sea, the Black Sea, and the Sea of Azov. It is fished by humans throughout much of its range.
The round fantail stingray or round stingray, is a poorly known species of stingray in the family Dasyatidae. It inhabits sandy, muddy, or rocky coastal habitats in the eastern Atlantic Ocean and the southern Mediterranean Sea. This dark-colored ray typically reaches a width of 1 m (3.3 ft), and can be identified by its nearly circular pectoral fin disk, short tail, and mostly bare skin. The round fantail stingray hunts for fishes and crustaceans on the sea floor, and exhibits an aplacental viviparous mode of reproduction. The International Union for Conservation of Nature (IUCN) does not yet have sufficient information to assess the conservation status of this species.
Bela oceanica is a species of sea snail, a marine gastropod mollusk in the family Mangeliidae.
Cymodocea nodosa is a species of seagrass in the family Cymodoceaceae and is sometimes known as little Neptune grass. As a seagrass, it is restricted to growing underwater and is found in shallow parts of the Mediterranean Sea and certain adjoining areas of the Atlantic Ocean.
The snake pipefish is a species of pipefish, from the family Syngnathidae, native to the northeastern Atlantic Ocean where they are generally found amongst algae close in to shore. It is the largest species of pipefish recorded in European waters and has spread into arctic waters in the early 2000s.
Clavularia crassa is a species of colonial soft coral in the family Clavulariidae. It is found in the eastern Atlantic Ocean and the Mediterranean Sea. It was first described in 1848 by the French zoologist Henri Milne-Edwards from a specimen collected off the coast of Algeria.
The common eagle ray or bullray is a species of fish in the family Myliobatidae. It inhabits the eastern Atlantic Ocean, the Mediterranean Sea and the south-western Indian Ocean.
Bathochordaeus, the giant larvaceans, is a genus of larvacean tunicates in the family Oikopleuridae.
Alloteuthis media, the midsize squid or little squid, is a species of squid in the family Loliginidae from the eastern Atlantic and the Mediterranean Sea. It is generally a by-catch species in trawl fisheries, although there is an active fishery in the western Mediterranean.
Althoffia is a monotypic genus of larvacean tunicates belonging to the family Oikopleuridae. The only species is Althoffia tumida.
Appendicularia is a genus of larvaceans in the family Fritillariidae.
Fritillaria is a genus of larvacean tunicates belonging to the family Fritillariidae.
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