Field Guide to Venomous and Medically Important Invertebrates ...

The stings of some sea anemones can be dangerous, causing pain and incapacity. Fortunately
most sea anemones have nematocysts that are too weak to penetrate human skin. Initial
symptoms vary from a prickly sensation to severe pain. The afflicted area can become red,
swollen, and blistered. Stings by the more dangerous anemones can cause shock and respiratory
distress. Balloon corallimorphs, Amplexidiscus fenestrafer, a colonial mushroom anemone,
produce stinging threads capable of penetrating wetsuits of unsuspecting divers causing
significant stinging. In some victims, such stings have been known to cause long-term
neurological damage. Treatment for sea anemone stings is the same as for jellyfish.
Figure 240. Balloon corallimorph (Amplexideiscus fenestrafer). Photo: source unknown.
Figure 241. Balloon corallimorph (Amplexideiscus fenestrafer), showing ―balloons.‖ Photo:
Shane Patterson.
Figure 242. Unidentified sea anemone. Photo: James Edmonds.
Sea Ferns
A few sessile hydroid colonies are capable of inflicting dangerous stings to people. Among the
more common sessile hydroid colonies are the Cypress Sea Fern, Aglaophenia cupressina, and
the White-Stinging Sea Fern, Lytocarpus philippinus, of the central and southern Pacific Ocean.
These animals have delicate fronds with rows of tiny polyps along each ―limb‖. Despite their
delicate appearance, the slightest brush against one of these hydroid colonies causes immediate
pain. The stinging begins as a patchy area of reddened skin and can develop into wheals within
30 minutes. The affected area may take up to a month to heal. Local anesthetic ointment is
effective as a pain reliever.
Figure 243. White-stinging sea fern (Lytocarpus philippinus). Photo: Theresa Zubi.