''Colossendeis'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

sea spider Sea spiders are marine arthropods of the class (biology), class Pycnogonida, hence they are also called pycnogonids (; named after ''Pycnogonum'', the type genus; with the suffix '). The class includes the only now-living order (biology), order P ...

(

class Class, Classes, or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used d ...

Pycnogonida Sea spiders are marine arthropods of the class Pycnogonida, hence they are also called pycnogonids (; named after ''Pycnogonum'', the type genus; with the suffix '). The class includes the only now-living order Pantopoda ( ‘all feet’), alongs ...

) belonging to the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Colossendeidae Colossendeidae is a family of sea spiders (class Pycnogonida). This family includes more than 100 species distributed among six genera. These sea spiders inhabit the deep sea mostly but are also found in shallower waters, especially in Antarctic ...

. These sea spiders are typically found in the deep sea. This genus includes the largest pycnogonids, with leg spans frequently ranging from 40 to 50 cm (16-20 in). The largest sea spider, ''

Colossendeis colossea ''Colossendeis colossea'' is a species of sea spider (class (biology), class Pycnogonida) in the family Colossendeidae. The species was species description, first described by Edmund Beecher Wilson, Edmund B. Wilson in 1881. It is the largest py ...

'', can reach a leg span of 70 cm (28 in). This genus also includes some

bioluminescent Bioluminescence is the emission of light during a chemiluminescence reaction by living organisms. Bioluminescence occurs in multifarious organisms ranging from marine vertebrates and invertebrates, as well as in some fungi, microorganisms inc ...

sea spiders.

Description

Sea spiders in this genus feature an unsegmented trunk, a low ocular

tubercle In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal. In plants A tubercle is generally a wart-like projectio ...

, and a well-developed abdomen. Chelifores are absent in adults. The palps and ovigers touch at their bases, and the strigilis is tightly curved with a strong terminal claw. Species in this genus have only four pairs of legs. The ventral surface of the second most proximal article (second coxa) of some or all of these legs features tiny genital pores.

Feeding

Sea spiders in this genus feed on

cnidarians Cnidaria ( ) is a phylum under kingdom Animalia containing over 11,000 species of aquatic invertebrates found both in fresh water, freshwater and marine environments (predominantly the latter), including jellyfish, hydroid (zoology), hydroids, ...

sponges Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and ar ...

bryozoans Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic animal, aquatic invertebrate animals, nearly all living in sedentary Colony (biology), colonies. Typically about long, they have a spe ...

, small

mollusks Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The num ...

, and small

polychaetes Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are m ...

Phylogeny

Although all species in this genus are eight-legged,

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

analysis based on molecular data indicates that this genus is

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

with respect to the ten-legged genus '' Decolopoda'' and the twelve-legged genus '' Dodecolopoda''; these two polymerous (extra-legged) genera are nested within the genus ''Colossendeis'' in a

phylogenetic tree A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA. In ...

. This paraphyly would normally make both ''Dodecolopoda'' and ''Colossendeis'' junior synonyms of ''Decolopoda'', the oldest name, and require all three genera to merge under the name ''Decolopoda''. To avoid this disruption, authorities keep these genera under different names and retain ''Colossendeis'' as a paraphyletic genus. The molecular evidence also indicates that both ''Decolopoda'' and ''Dodecolopoda'' are nested within a

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

group containing the "longitarsal" species in the genus ''Colossendeis''. The sea spiders in this "longitarsal"

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

feature legs in which the three most distal articles (claw, propodus, and tarsus) taken together are at least three-quarters the length of the fourth most distal article (second tibia). This clade includes not only

Antarctic The Antarctic (, ; commonly ) is the polar regions of Earth, polar region of Earth that surrounds the South Pole, lying within the Antarctic Circle. It is antipodes, diametrically opposite of the Arctic region around the North Pole. The Antar ...

species of ''Colossendeis'' such as '' C. australis'' and '' C. glacialis'' but also widespread taxa such as '' C. megalonyx'' and '' C. robusta''. In "brevitarsal" species, such as '' C. macerrima'', the three most distal articles are instead much shorter relative to the second tibia.

Species

There are 72 species: * '' Colossendeis acuta'' Stiboy-Risch, 1993 * '' Colossendeis adelpha'' Child, 1998 * '' Colossendeis angusta'' Sars, 1877 * '' Colossendeis aperta'' Turpaeva, 2005 * '' Colossendeis arcanus'' Turpaeva, 2008 * '' Colossendeis arcuata'' A. Milne-Edwards, 1885 * '' Colossendeis australis'' Hodgson, 1907 * '' Colossendeis avidus'' Pushkin, 1970 * '' Colossendeis belekurovi'' Pushkin, 1993 * '' Colossendeis bicincta'' Schimkewitsch, 1893 * '' Colossendeis bouvetensis'' Dietz, Pieper, Seefeldt & Leese, 2015 * '' Colossendeis brevirostris'' Child, 1995 * '' Colossendeis bruuni'' Fage, 1956 * '' Colossendeis clavata'' Meinert, 1899 * ''

'' Wilson, 1881 * '' Colossendeis concedis'' Child, 1995 * '' Colossendeis cucurbita'' Cole, 1909 * '' Colossendeis curtirostris'' Stock, 1963 * '' Colossendeis dalli'' Child, 1995 * '' Colossendeis drakei'' Calman, 1915 * '' Colossendeis elephantis'' Child, 1995 * '' Colossendeis enigmatica'' Turpaeva, 1974 * '' Colossendeis ensifer'' Child, 1995 * '' Colossendeis fijigrypos'' Bamber, 2004 * '' Colossendeis fragilis'' Pushkin, 1993 * '' Colossendeis gardineri'' Carpenter, 1907 * '' Colossendeis geoffroyi'' Mane-Garzon, 1944 * '' Colossendeis glacialis'' Hodgson, 1907 * '' Colossendeis gracilis'' Hoek, 1881 * '' Colossendeis grassus'' Pushkin, 1993 * '' Colossendeis hoeki'' Gordon, 1944 * '' Colossendeis insolitus'' Pushkin, 1993 * '' Colossendeis korotkevitschi'' Pushkin, 1984 * '' Colossendeis kurtchatovi'' Turpaeva, 1993 * '' Colossendeis leniensis'' Pushkin, 1993 * '' Colossendeis leptorhynchus'' Hoek, 1881 * '' Colossendeis longirostris'' Gordon, 1938 * '' Colossendeis losinskii'' Turpaeva, 2002 * '' Colossendeis macerrima'' Wilson, 1881 * '' Colossendeis media'' Hoek, 1881 * '' Colossendeis megalonyx'' Hoek, 1881 * '' Colossendeis melancholicus'' Stock, 1975 * '' Colossendeis mica'' Pushkin, 1970 * '' Colossendeis microsetosa'' Hilton, 1943 * '' Colossendeis minor'' Schimkewitsch, 1893 * '' Colossendeis minuta'' Hoek, 1881 * '' Colossendeis mycterismos'' Bamber, 2004 * '' Colossendeis nasuta'' Hedgpeth, 1949 * '' Colossendeis notialis'' Child, 1995 * '' Colossendeis oculifera'' Stock, 1963 * '' Colossendeis peloria'' Child, 1994 * '' Colossendeis perforata'' Turpaeva, 1993 * '' Colossendeis pipetta'' Stock, 1991 * '' Colossendeis potentis'' Turpaeva, 2008 * '' Colossendeis proboscidea'' (Sabine, 1824) * '' Colossendeis pseudochelata'' Pushkin, 1993 * '' Colossendeis robusta'' Hoek, 1881 * '' Colossendeis rostrata'' Turpaeva, 1994 * '' Colossendeis scoresbii'' Gordon, 1932 * '' Colossendeis scotti'' Calman, 1915 * '' Colossendeis sinuosa'' Stock, 1997 * '' Colossendeis spicula'' Child, 1994 * '' Colossendeis stramenti'' Fry & Hedgpeth, 1969 * '' Colossendeis subminuta'' Schimkewitsch, 1893 * '' Colossendeis tasmanica'' Staples, 2007 * '' Colossendeis tenera'' Hilton, 1943 * '' Colossendeis tenuipedis'' Pushkin, 1993 * '' Colossendeis tethya'' Turpaeva, 1974 * '' Colossendeis tortipalpis'' Gordon, 1932 * '' Colossendeis vityazi'' Turpaeva, 1973 * '' Colossendeis weddellensis'' Turpaeva, 2008 * '' Colossendeis wilsoni'' Calman, 1915

Description

Feeding

Phylogeny

Species

References

Further reading