Giant Pacific Octopus ( Enteroctopus dolfeini )
|Rochebrune & Mabille , 1889|
The giant octopus ( Enteroctopus ) are a genus within the family of real octopuses . The genus Enteroctopus comprises four previously described species , the type species is Enteroctopus megalocyathus .
The species of the genus are large to very large, they reach coat lengths of up to 60 cm and total lengths of at least 3 m. The ovoid coat is muscular. Non-mineralized, reduced remnants of a shell within the mantle (stylets) are present. The arms are long and muscular, typically 3.5 to 5 times the length of the coat. The arms are about the same length, in some species the dorsal (back) pairs of arms are slightly longer. The webbing is moderate to deep. It extends to about 20 to 30% of the arm length on the longest arms and is deepest on the side and least deep on the ventral (stomach-side) arms. The suction cups sit in two rows, enlarged suction cups are available in some species. The funnel organ (funnel) is W-shaped. The radula consists of nine elements, seven rows of teeth and two edge plates. An ink pouch is provided, as are small anal flaps.
In the males, the third right arm is transformed into a hectocotylus , the elongated reproductive organ is large. The ligula is extremely long (about 20% of the arm's length) and narrow, the calamus tiny. The spermatophores are extremely long with up to seven times the mantle length, the small eggs are laid in garland-shaped strands.
Giant octopuses are typically reddish brown to orange, although the color can be uniform to spotty. False eyespots (ocelli) are missing. Dorsally and slightly in front of the center of the mantle is a transverse pair of white spots. The skin is soft, semi-gelatinous, with distinct longitudinal dorsal and lateral folds and wrinkles. A relief-like skin pattern (patch and groove system, patch-and-groove topology) is present. There are conspicuous papillae on the coat and head. Four elongated, diamond-shaped papillae are located dorsally in the middle of the mantle, with one or two large, lobed papillae above each eye. A skin ridge around the side edge of the mantle is missing.
distribution and habitat
Giant octopuses are found in temperate and cooler waters of the Indian and Pacific Oceans, as well as in the southern Atlantic. The species live near the coast in the intertidal zone and in the deep sea up to at least 1500 m and inhabit reefs and soft sediment substrates.
Giant octopuses are often mistakenly spoken of when in reality giant squids are meant. While giant squids have ten arms, two of which are transformed into tentacles , giant octopuses have eight arms. They should not be confused with the kraken , a mythical creature in Norse mythology (see giant octopus (mythology) ).
Research history and systematics
Rochebrune and Mabille created the genus in 1889 on the basis of the new species Enteroctopus membranaceus and also added Enteroctopus megalocyathus , previously Octopus megalocyathus , to the new genus. Since Enteroctopus membranaceus was the first species in the genus, it is sometimes considered a type species of the genus. However, Enteroctopus membranaceus is often regarded as a noun dubium because the original description is not considered sufficient, the holotype was a juvenile specimen and, moreover, no longer exists. Robson (1929) saw Enteroctopus membranaceus as a junior synonym of Enteroctopus megalocyathus , other authors follow the views on Enteroctopus membranaceus and thus regard Enteroctopus megalocyathus as a type species .
The genus includes four species:
- Enteroctopus dofleini (Pacific giant octopus) ( Wülker , 1910)
- Enteroctopus magnificus (South African giant octopus) ( Villanueva et al., 1992)
- Enteroctopus megalocyathus (South Pacific giant octopus ) ( Gould , 1852)
- Enteroctopus zealandicus ( Benham , 1944)
- Mark Norman: Cephalopods A World Guide. 319 pp., ConchBooks, Hackenheim 2000 ISBN 3-925919-32-5
- Enteroctopus at World Register of Marine Species (WoRMS)
- M. D. Norman, JK Finn, FG Hochberg: Family Octopodidae. In P. Jereb, CFE Roper, MD Norman, JK Finn (eds.) Cephalopods of the world. An annotated and illustrated catalog of cephalopod species known todate. Volume 3. Octopods and Vampire Squids. 2014, FAO Species Catalog for Fishery Purposes. No. 4, vol. 3. Rome, FAO. P. 122. ( Online )
- AT De Rochebrune, Jules Mabille: Mollusques. In: Mission scientifique du cap Horn , 1882–1883. Volume: 6, Issue: 2, 1889, page H. 7 and H. 8. ( Online )