| Pycnogonum | |
|---|---|
 | |
| Pycnogonum litorale | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Chelicerata |
| Class: | Pycnogonida |
| Order: | Pantopoda |
| Family: | Pycnogonidae |
| Genus: | Pycnogonum Brünnich, 1764 [1] |
| Species | |
See text | |
Pycnogonum is a genus of sea spiders in the family Pycnogonidae. It is the type genus of the family. [2]
The generic name literally means “dense knees”. Pycnogonum combines the prefix pycno- (from ‘dense’ in Greek) with the Greek word for "knee": gony ( γόνυ ). [2] [3] [4]
Members of the genus Pycnogonum have squarish bodies with a tough integument and a few hairs. The cephalon (the anterior end of the body which is fused with the first segment of the trunk) has a long smooth proboscis and a low tubercle on which the eyes are set. There are no chelicerae or palps and these sea spiders use their proboscis to suck juices from their prey. On the first segment of the trunk of males there are small ovigerous legs with nine segments. The larvae are carried around by the males on these appendages. The four pairs of ambulatory legs are short but strong, with well-developed terminal claws. The genital openings are on the second segment of the posterior pair of legs. [5]
The World Register of Marine Species lists the following species: [1]
Sea spiders are marine arthropods of the order Pantopoda, belonging to the class Pycnogonida, hence they are also called pycnogonids. They are cosmopolitan, found in oceans around the world. The over 1,300 known species have leg spans ranging from 1 mm (0.04 in) to over 70 cm (2.3 ft). Most are toward the smaller end of this range in relatively shallow depths; however, they can grow to be quite large in Antarctic and deep waters.
Colossendeidae is a family of sea spider. Like most sea spiders, species in this family have four pairs of legs, except for three species with five leg pairs, including the first polymerous sea spider discovered, and one giant species that was the first sea spider discovered with six leg pairs.
Hedgpethia is a genus of sea spider, in the family Colossendeidae. The genus was named after the marine biologist and sea spider specialist Joel Hedgpeth.
The Asilidae are the robber fly family, also called assassin flies. They are powerfully built, bristly flies with a short, stout proboscis enclosing the sharp, sucking hypopharynx. The name "robber flies" reflects their expert predatory habits; they feed mainly or exclusively on other insects and, as a rule, they wait in ambush and catch their prey in flight.
Palaeotherium is an extinct genus of perissodactyl ungulate known from the Mid Eocene to earliest Oligocene of Europe. First described by French naturalist Georges Cuvier in 1804, Palaeotherium was among the first Paleogene mammals to be described.
Gonyleptidae is a neotropical family of harvestmen with more than 800 species, the largest in the suborder Laniatores and the second largest of the Opiliones as a whole. The largest known harvestmen are gonyleptids.
Nymphonidae is a family of sea spiders which has representatives in all the oceans. This family contains some 250 species, most of which are found in the genus Nymphon. Nymphonid bodies are between 1 and 15 mm long, the extent between the points of the legs reaching 150 mm. Most species are predators of hydroids. Like most sea spiders, species in this family have four pairs of legs, except for Pentanymphon antarcticum, which has five pairs, and Sexanymphon mirabilis, which has six pairs.
Nymphon is a genus of sea spiders in the family Nymphonidae. The species of sea spiders within the genus Nymphon are all benthic organisms and are found in abyssal and bathyal areas of the ocean. This is a fully marine group and can be found at various depths ranging from the littoral zones to the deep sea. They are found in most major oceans across the globe with a strong distribution around polar regions: Arctic and Antarctic waters. Out of the sea spider genus, Nymphon is the most rich, with a majority of the species within the genis being found in the Southern Ocean region. This genus may also contain bioluminescent species.
Pycnogonidae is a family of sea spiders.
Ammotheidae is the most diversified group of the class Pycnogonida, with 297 species described in more than 20 genera, of which only Nymphopsis and Sericosura were found to be monophyletic. Despite its internal taxonomic uncertainty, studies on 18S rRNA supports its monophyly, and the subdivision on Achelinae and Ammotheinae subfamilies.
Achelia is a genus of pycnogonids in the family Ammotheidae.
Tanystylum is a genus of pycnogonids in the family Ammotheidae.
Nymphon gracile is a species of sea spider first described by William Elford Leach in 1863. The species highly resembles other members of the genus Nymphon, and species identification from morphological traits alone is, therefore, a complex task.
Colossendeis is a genus of sea spider belonging to the family Colossendeidae.
Callipallene is a genus of sea spiders in the family Callipallenidae. There are more than 30 described species in Callipallene.
Palaeoisopus is a monotypic genus of fossil pycnogonid, known only by one species, Palaeoisopus problematicus, discovered from the Lower Devonian Hunsrück Slate of Germany. It have several characters unusual for a pycnogonid, such as swimming legs with alternating size, medially-arranged eyes, and most significantly, a long, segmented abdomen, which were highly reduced in modern counterparts.
Propallene longiceps is a species of sea spider in the family Callipallenidae. It is found in shallow water in the western Pacific Ocean.
Pycnogonum litorale is a marine arthropod in the family Pycnogonidae, the sea spiders. It is found in the northern Atlantic Ocean, the North Sea, the English Channel and the western Mediterranean Sea.
Phoxichilidium is a genus of sea spiders within the family Phoxichilidiidae. Members of this genus can be found in all oceans at depths up to 1074 meters.
From Neo-Latin Pycnogonida, class name, from Pycnogonum, type genus: Greek puknos, thick + Greek gonu, knee; see genu- in Indo-European roots.
pycnogonids (meaning "dense-knees")