although this does not afford complete protection. A collector should never carry a live cone inside a wet suit,
clothing pocket, or buoyancy compensator pocket.
Octopuses
Life and Habits. Octopuses and cuttlefish are cephalopods that are usually harmless and retiring. On
occasion, they are noted to manifest "curiosity" or "play behavior," by navigating mazes or manipulating
objects without intent to feed or create a habitat. True octopuses are inhabitants of warmer waters and have
little tolerance for extremes in salinity. They prefer rocky bottoms and rock pools in the intertidal zones. The
entertainment media have created the image of a giant creature that envelops its victim in a maze of tentacles
and suction cups. The truth is that most dangerous (envenoming) creatures are smaller than 10 to 20 cm and
do not squeeze their victims at all. However, there are reports in the South Pacific of breath-hold
spearfishermen drowned while hunting octopuses. The method used to kill the animals was to allow an
octopus to cling to a diver, who would bite the animal between the eyes as the combatants surfaced.
Apparently, the octopuses were large enough (4 m tentacle span) to resist the technique.
Octopus bites are rare but can result in severe envenomations. Fatalities have been reported from the
bites of the Australian blue-ringed (or "spotted") octopuses, Octopus (Hapalochlaena) maculosus and O. (H.)
lunulata. These small creatures, which rarely exceed 20 cm in length with tentacles extended, are found
throughout the Indo-Pacific (Australia, New Zealand, New Guinea, Japan) in rock pools, under discarded
objects and shells, and in shallow waters, posing a threat to curious children, tidepoolers, fossickers, and
unwary divers. Divers rarely spot them in water deeper than 3 m. In Australian waters, Hapalochlaena
maculosa, the southern species, is smaller and yellow. H. lunulata is found in the north; larger, darker, and
predominantly brownish, it favors the warmer tropical water. When either animal is at rest, it is covered with
dark brown to yellow-ochre bands over the body and arms, with superimposed blue patches or rings. When
the animal is excited or angered, the entire body darkens and the blue circles or stripes glow iridescent
peacock blue, a trait shared by other animals such as the peacock flounder (Bothus lunatus). The colorful
appearance is attractive to small children, who can easily handle the 25 to 90 g animal. The smallish Octopus
joubini of the Caribbean, which lives in small shells and empty containers such as submerged bottles, is
dangerous to a lesser degree; envenomation causes pain followed by numbness, fever, and nausea. The large
common octopus O. vulgaris is nontoxic. Many octopuses can release inky fluid into the water, which is used
to confuse attackers; this mechanism is not present in the blue-ringed octopus. The chameleon-like changing
of colors to match the surroundings is accomplished with pigment cells (chromatophores).
Venom and Venom Apparatus. The venom apparatus of the octopus consists of the anterior and
posterior salivary glands, salivary ducts, buccal mass, and beak. The mouth is located ventrally and centrally
at the base of the tentacles and is surrounded by a circular lip fringed with fingerlike papillae, leading into a
muscular pharyngeal cavity. This anatomical complex (buccal mass), concealed by the tentacles, is fronted by
two parrotlike, powerful, and chitinous jaws (the "beak"), which bite and tear with great force at food held by
the suckers. The salivary glands, particularly the posterior, secrete maculotoxin (or cephalotoxin) via the
salivary ducts into the pharynx. This venom, normally released into the water to subdue crabs, may be
injected into the victim with great force through the dermis down to the muscle fascia. Only the venom of H.
maculosa has been extensively studied. The toxin, maculotoxin (molecular weight less than 5000), contains at
least one fraction identical to tetrodotoxin (C
11
H
17
O
8
N
3
) of molecular weight 319.3, which blocks peripheral
nerve conduction by interfering with sodium conductance in excitable membranes. This paralytic agent
rapidly produces neuromuscular blockade, notably of the phrenic nerve supply to the diaphragm, without any
apparent direct cardiotoxicity. It has been estimated that enough venom (25 g) may be present in one adult
octopus to paralyze 750 kg of rabbits or 10 adult victims. An adult blue-ringed octopus can inject a second
fatal dose of toxin after a 1-hour interval. The venom is active on ingestion or by parenteral administration,
the latter being much more effective. Other components of the venom, which include hyaluronidase,
histamine, 5-hydroxytryptamine, tyramine, serotonin, and "hapalotoxin" (still not confirmed as being present),
are not thought to be major contributors to the clinical effects of an octopus bite. Because most venoms and
toxins with molecular weights less than 30,000 are poor antigens, octopus venom elicits no good antivenom.
Clinical Aspects. Most victims are bitten on the hand or arm, as they handle the creature or "give it a
ride." No blue-ringed octopus bites have yet been reported from an animal in the water. An octopus bite
usually consists of two small puncture wounds produced by the chitinous jaws. The bite goes unnoticed or
