Maori octopus, New zealand octopus
Macroctopus maorum is known more commonly as the Maori octopus or the New Zealand octopus (wheke in Maori). They can also be known as Pinnoctopus cordiformis, is found in the waters around New Zealand and southern Australia. M. maorum is one of the largest and most aggressive octopus species living in the New Zealand and Australian waters. They feed mainly on crustaceans and fish. Although they have a short life span, the females lay thousands of eggs and are very protective of them.
A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton. Phytoplankton are usually photosynthet...
Ambush predators are carnivorous animals that capture or trap prey by stealth, luring, or by (typically instinctive) strategies utilizing an elemen...
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starts withMacroctopus maorum is a large octopus and it is regularly described as a ‘robust’ species, it is a member of the Octopus macropus species complex. The morphological traits characteristic of this complex are a high number of gill lamellae, a robust conical copulatory organ and arms of varying length with long unequal dorsal arms generally four to six times longer than the mantle. Although being unequal, their arms are said to be long and evenly tapering and Macroctopus maorum are even known to regrow arms when one has been lost. Being the largest member of its complex arm span is said to exceed 3 metres (9.8 ft). They have four to six suckers on the first and second arm pairs which are usually about 40 millimetres (1.6 in) in size. Suckers are arranged in two rows down the arm length. There is thought to be no correlation between sexes and size of suckers; however, there was an increase in sucker size with body mass increase. Coloration of this species can vary Macroctopus maorum can be distinguished from other species by the colour, they will be either orange-brown or dark purple-grey. The octopus has numerous small iridescent white spots on the web, arms and dorsal arm crown but there are no spots present on the mantle. Macroctopus maorum has 12–14 gill lamella per demibranch, the mantle is described as broadly ovoid and exhibits a skin pattern of longitudinal ridges. Along the dorsum there are five rows of unbranched papillae and two more papillae appear individually above the eyes. Octopus papillae are camouflage specialised with the ability to change shape, such as by extending in and out from the body. Male M. maorum have a small ligula, the ligula is a specialised arm tip on the hectocotylized arm which grips to allow the transfer of spermatophores. Within the complex O. macropus, Macroctopus maorum is thought to be the largest member. In a study estimating M. maorum size based on a sample of 90 beaks, the largest individual found had a body length of 2.0 metres (6 ft 7 in) and body mass of 12 kg. Macroctopus maorum has an upper beak and lower beak, the upper beak can be used to differentiate Macroctopus maorum and Enteroctpus zealandicus as it has a lack of overlap in the ratio of upper hood length and upper chest length. Macroctopus maorum hatchlings are usually about 5.06 mm in size, they have 7–8 suckers per arm and each dorsal arm will have 6–11 chromatophores.
M. maorum lives in the benthic zone in soft-sediment and rubble habitats with depths of 0-549m and will sometimes forage in nearby hard-reef habitats and are less common at the fringes between reefal and soft sediment habitats. Rather than settling in a specific location, M. maorum uses temporary shelters. In Tasmania, young M. maorum have been observed settling in intertidal rock pools. Similar sightings of M. maorum in intertidal rock pools have been reported during the summer months in Kaikoura and Banks Peninsula.
A study of M. maorum off the coast of southeastern Tasmania found evidence of 12 different species in the stomachs of sampled octopuses with the dominant prey being the crab P. gaimardii and other M. maorum. This is a low number of prey species compared to other species of octopus and it is assumed that the diet of M. maorum in Southeastern Tasmania is more diverse than results indicated in the study. M. Maorum will eat bivalves, crustaceans and fish but are selective and show preference to lobster, crabs and scallops. As is the case with other octopus species, M. maorum injects prey with a toxin that slowly liquefies flesh so that it can be more easily digested. Cannibalism is a common behavior for many species of octopus in the order of large eating small, however small M. maorum are known to attack larger octopus particularly Octopus tetricus where habitats overlap. M. maorum feeds mainly at night unless food is scarce in which case it must forage during the day. M. maorum is an extremely evolved hunter with a range of hunting methods including stalking, ambush, jet-propulsion and digging. When executing different hunting methods colour and texture are adjusted, often by darkening and erection of papillae. Prey such as crabs are pounced on using the speed of jet propulsion and prey is trapped under the octopus’s web in what is appropriately called the parachute position. Alternatively, in a situation where prey is nearby the octopus will simply snatch it with one of its tentacles. In the case of prey escaping and hiding M. maorum will persistently dig to uncover prey by pushing material into its web and dumping the removed material by the entrance to its home.
During mating, the male Macroctopus maorum will be on top pinning down the female and usually overpowering the female physically or pouncing on them. The male will inserts a sperm packet by passing it along the arms to the oviduct of the female. When it get near to the oviduct, the end of the spermatophore burst open and released the sperm. Male octopus will then become senescent and die after mating. Female "Macroctopus maorum mature and mate during March and October.
