Largest Organisms - Animals - Invertebrates - Arthropods (Arthropoda)

Arthropods (Arthropoda)

The largest arthropod known to have existed is the eurypterid (sea scorpion) Jaekelopterus, reaching up to 2.5 m (8.2 ft) in body length, followed by the millipede relative Arthropleura at around 2.1 m ( 7 ft) in length. Among living arthropods, the Japanese spider crab (Macrocheira kaempferi) is the largest in overall size, the record specimen, caught in 1921, had an extended arm span of 3.8 m (12.5 ft) and weighed about 19 kg (41 lb). The heaviest is the American lobster (Homarus americanus), the largest verified specimen, caught in 1977 off of Nova Scotia weighed 20kg and its body length was 1.1 m (3.5 ft). The largest land arthropod and the largest land invertebrate is the coconut crab (Birgus latro), up to 40 cm (1.3 ft) long and weighing up to 4 kg (8.8 lb) on average. Its legs may span 1 m (3 ft).

  • Arachnids (Arachnida)
The largest species of arachnid by length is probably the Giant Huntsman spider (Heteropoda maxima) of Laos, which in 2008 replaced the Goliath birdeater (Theraphosa blondi) of Northern South America as the largest spider by leg-span. However the most massive arachnids, of comparable dimensions and possibly even greater mass, are the Chaco golden knee, Grammostola pulchripes, and the Brazilian salmon pink, Lasiodora parahybana. The huntsman spider may span up to 29 cm (11 in) across the legs, while in the New World "tarantulas" like Theraphosa it can range up to 26 cm (10 in). In Grammostola, Theraphosa and Lasiodora, the weight is projected to be up to at least 150 g (5.3 oz) and body length is up to 10 cm (3.9 in). The largest of the scorpions is the species Heterometrus swammerdami of the Indian subcontinent, which have a maximum length of 29.2 cm (11.5 in) and weigh around 60 g (2.1 oz). Another extremely large scorpion is the African Imperial scorpion (Pandinus imperator), which can weigh 57 g (2 oz) but is not known to exceed a length of 23 cm (9.1 in). However, they were dwarfed by Pulmonoscorpius kirktonensis, a giant extinct species of scorpion from Scotland, at an estimated length of 0.7 m (2.3 ft) and weight of 15 kg (33 lb), and the aquatic Brontoscorpio, at up to 1 m (3.3 ft) and a similar weight.
  • Branchiopods (Branchiopoda)
The largest of these primarily freshwater crustaceans is probably Branchinecta gigas, which can reach a length 10 cm (3.9 in).
  • Centipedes (Chilopoda)
The biggest of the centipedes is Scolopendra gigantea of the neotropics, reaching a length of 33 cm (13 in).
  • Millipedes (Diplopoda)
Two species of millipede both reach a very large size Archispirostreptus gigas of East Africa and Scaphistostreptus seychellarum, endemic to the Seychelles islands. Both of these species can slightly exceed a length of 28 cm (11 in) and measure over 2 cm (0.79 in) in diameter.
  • Barnacles and allies (Maxillopoda)
The largest species is a copepod (Pennella balaenopterae), known exclusively as a parasite from the backs of fin whales (Balaenoptera physalus). The maximum size attained is 32 cm (about 13 in). The largest of the barnacles is the giant acorn barnacle, Balanus nubilis, reaching 7 cm (2.8 in) in diameter and 12.7 cm (5 in) high.
  • Horseshoe crabs (Merostomata)
The four modern horseshoe crabs are of roughly the same sizes, with females measuring up to 60 cm (2 ft) in length and 5 kg (11 lb) in weight. Easily the best known species is Limulus polyphemus of North America.
  • Ostracods (Ostracoda)
The largest living representative of these small and little-known but numerous crustaceans is the species Gigantocypris australis females of which reaching a maximum length of 3 cm (1.3 in).
  • Amphipods, isopods, and allies (Peracarida)
The largest species is the giant isopod (Bathynomus pergiganteus), which can reach a length of 45 cm (18 inches) and a weight of 1.7 kg (3.7 lb).
  • Sea spiders (Pycnogonida)
The largest of the sea spiders is the deep-sea species Colossendeis colossea, attaining a leg span of nearly 60 cm (2 ft).
  • Remipedes (Remipedia)
The largest of these cave-dwelling crustaceans is the species Godzillius robustus, at up to 4.5 cm (1.8 in).
  • Trilobites (Trilobita)
Some of these extinct marine arthropods exceeded 60 cm (24 inches) in length. A nearly complete specimen of Isotelus rex from Manitoba attained a length over 70 cm (27 in), and a Ogyginus forteyi from Portugal was almost as long. Fragments of trilobites suggest even larger record sizes. An isolated pygidium of Hungioides bohemicus implies that the full animal was 90 cm (36 in) long.

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