Other starfish which might envenom humans are those of genus Echinaster. The slime (cushion) star
Pteraster tessalatus, which inhabits Pacific coastal waters from Puget Sound to Alaska, generates the unique
defense of copious gelatinous or rubbery, poisonous mucus to repel natural enemies. No human injuries have
been reported to date.
Clinical Aspects. The ice pick-like spine of Acanthaster planci can penetrate the hardiest of diving
gloves. Most spines are composed of porous crystalline magnesium calcite, articulated at the base and
extremely sharp, with three raised cutting edges at the tips. As the spine enters the skin, it carries venom into
the wound, with immediate pain, copious bleeding, and mild edema. The pain is generally moderate and self-
limited, with remission over a period of 1/2 to 3 hours. The wound may become dusky or discolored. Multiple
puncture wounds may result in acute systemic reactions, including paresthesias, nausea, vomiting,
lymphadenopathy, and muscular paralysis. If a spine fragment is retained, a granulomatous lesion may
develop akin to that from a sea urchin puncture wound. If the victim has been previously sensitized, he or she
may suffer a prolonged reaction lasting for weeks and consisting of local edema and pruritus. Contact with
other less injurious starfish may induce a pruritic papulourticarial eruption (irritant contact dermatitis).
Treatment. Immersion therapy may provide some relief from the pain. The wound should immediately
be immersed into nonscalding hot water to tolerance (113
o
F or 45
o
C) for 30 to 90 minutes or until there is
significant pain relief. The pain is rarely severe enough to require local anesthetic infiltration. The puncture
wound should be irrigated and explored to remove all foreign material. Because of the stout nature of the
spines, it is rare to retain a fragment. However, if any question of a foreign body exists, a soft tissue
radiograph often identifies the fractured spine. Not infrequently the victim suffers an indolent contact
dermatitis from handling a starfish, such as Solaster papposus, the sun or rose star. The dermatitis may be
managed in standard fashion with topical solutions, such as calamine with 0.5% menthol, or a corticosteroid
preparation. Systemic therapy is supportive. Granulomas from retained spine fragments may require excision.
Starfish that have ingested poisonous shellfish are themselves toxic on ingestion.
Sea Urchins
Sea urchins are free-living echinoderms that have an egg-shaped, globular, or flattened body. A hard
skeleton (test) comprised of fused calcareous plates surrounds the viscera and is covered by regularly arranged
spines and triple-jawed (pincer-like) pedicellariae, the latter of which (globiferous, or glandular) are
sometimes used for defense. Urchins are nocturnal and omnivorous (mostly in pursuit of algae) eaters, yet are
shy, nonaggressive, and slow-moving animals found on rocky bottoms or burrowed in sand and crevices.
Their bathymetric range extends from the intertidal zone to great depths. The raw or cooked gonads of several
species are eaten as great delicacies by humans.
The venom apparatuses of sea urchins consist of the hollow, venom-filled spines and the triple-jawed
globiferous pedicellariae. Venom may also be released from within a thin integumentary sheath on the
external surface of the spines of certain urchins.
The spines of sea urchins, formed by the calcification of a cylindrical projection of subepidermal
connective tissue, may either be non-venom-bearing, with solid blunt and rounded tips, or venom-bearing
with hollow, long, slender, and sharp needles. These are extremely dangerous to handle; the spines, which are
attached to the shell with a modified ball-and-socket joint, are brittle and break off easily in the flesh, lodging
deeply and making removal difficult. They are keen enough to penetrate rubber gloves and fins. Diadema
setosum (black sea urchin) spines may exceed 1 foot in length. Echinothrix species also carry lengthy spines.
The purple sea urchin Strongylocentrotus purpuratus of California has much shorter spines. The genera
Asthenosoma and Aerosoma have special venom organs (sacs) on the sharp tips of the aboral spines, which
introduce the potent venom.
Pedicellariae are small, delicate seizing organs attached to the stalks scattered among the spines. These
are considered to be modified spines with flexible heads. Globiferous pedicellariae are typified by those found
in Toxopneustes pileolus (flower urchin) and Tripneustes species, and have globe-shaped heads which contain
the venom organs. The terminal head, with its calcareous pincer jaws (2 to 4; usually 3), is attached by the
stalk to the shell plates of the sea urchin. The outer surface of each opened "jaw" is covered by a large venom
gland, which is triggered to contract with the jaw on contact. When the sea urchin is at rest in the water, the
jaws are extended, slowly moving about. Anything that touches with them is seized. As long as the object is
moving, the pedicellariae continue to bite and envenom. Once a pedicellaria attaches to a victim, it will be
