Species group: Octopus and Squid
Other common names: Mediterranean Octopus, Caribbean Octopus
Scientific name: Octopus vulgaris
Collected in huge numbers for the food trade, young Common Octopuses are sometimes plucked from nets and funneled to local animal dealers for sale to aquarists. Although much favored due to their size and intelligence, the Common Octopus grows too large for most home aquariums, and is best left to serious pros with ample space…and money!
This most widely-distributed of the world’s Octopuses is found in the Atlantic, Pacific, and Indian Oceans, and the Mediterranean Sea, in regions ranging from tropical to temperate.
The Common Octopus may be found in quite shallow water out to depths of at least 150 meters (492 ft). It is very adaptable, sheltering among coral reefs, rocks, wrecks, empty shells, and discarded tires and other debris.
Appearance / health:
The stocky mantle (head and body) averages 20 cm (8 in) in length, and the thick arms may reach 80 cm (32 in), providing a total arm-span of 1.5 m (5 ft). The highly-changeable skin color is usually mottled yellow, green, brown or gray. The skin’s usually typically texture is subject to change as well.
The Common Octopus’s natural life span is only 12 – 18 months, and it is extremely sensitive to copper, ammonia, and nitrates in the water. When startled or stressed, Octopuses release a black, inky liquid designed to confuse predators. In the confines of an aquarium, however, ink can prove fatal to an Octopus.
Behavior / temperament:
Octopuses are surprisingly-intelligent, quickly figuring-out how to extract food from closed jars, distinguish shapes, and recall what they have learned. Several species have been observed to leave their aquariums, negotiate floors, catch shrimp in other tanks, and return to their home base!
No Octopus, however calm, should be handled or hand-fed, as all produce venom and can deliver a painful bite with their hard, curved beaks. While fatalities from the commonly-sold species are unknown, the possibility of a serious allergic reaction to their venom must be considered.
An adult Common Octopus requires a well-filtered 250 gallon or larger aquarium that has been cycled for 2-3 months and is provisioned with a thin layer of sand. They are consummate escape artists, so the filter canopy must be weighted or secured with clips and duct tape, and all hose/wire openings must be sealed. Wet/dry and other out-of-tank filters are the best options, and a protein skimmer is advisable.
Lighting should be subdued; a red night-viewing bulb will allow you to observe your pat’s nocturnal wanderings. Caves, preferably of live rock, are essential. Clay flower pots, empty shells, and other shelters will also be accepted. All rockwork must be secured, using silicone if necessary, as Octopus are incredibly strong – and they seem to delight in trashing whatever homes we provide for them!
The Common Octopus should be maintained at a specific gravity (salinity) of 1.025-1.026 and a pH of 8-8.4. Ideal temperatures vary from 21-28 C (70-82 F), depending on the origin of the individual within the huge natural range.
Youngsters and newly-caught adults often refuse all but live shrimp and crabs; green, fiddler, Asian shore, and other crabs may be collected or purchased at bait shops. In time, most pets can be weaned to non-living foods. The diet should be varied, and include crabs, clams, mussels, scallops, snails, abalone, and spearing and other fishes and invertebrates.
Captive breeding is rare, with fights and/or predation being the usual result when two individuals are introduced. Female Common Octopuses guard their eggs within caves or other shelters, cleaning and aerating them and blocking the entrance with rocks and shells. They generally do not feed during the 2-5 month incubation period, and usually expire shortly after their 50,000-500,000 eggs hatch.
Written by Frank Indiviglio