Field Guide to Venomous and Medically Important Invertebrates ...

exploration of the wounds may be necessary in severe cases. Local antibiotic therapy after
removal of the spines reduces chances of secondary infection.
Figure 252. Unidentified sea urchin. Photo: Olof Aldin.
Figure 253. Sea urchin (Strongylocentrotus purpuratus). Photo: Humbolt State University
Sea Cucumbers
The final echinoderm group known to be dangerous to people is the sea cucumbers (Class
Holothuroidea), although dangerous encounters with these animals are rare. Most problems
associated with sea cucumbers are due to consuming the flesh of poisonous species that may
result in death. However, some species when threatened or handled will eviscerate their
intestines and white sticky threads used for defensive purposes. These threads and excreted
mucus contain a toxin known as holothurin which can cause skin and eye irritation. Reported
reactions to the toxin include burning, inflammation, redness, intense pain, and damage to the
eyes sometimes causing blindness. Some species of sea cucumbers also ingest other stinging
animals and incorporate and excrete those toxins for their own defense.
Figure 254. An unidentified sea cucumber. Photo: Kieran Boyce.
Figure 255. A sea cucumber (Parastichopus californicus). Photo: John Harvey.
Leeches
Annelid Worms
Leeches belong to the Phylum Annelida which also includes the earthworms. All leeches have
34 body segments although their form and structure varies widely. Some land leeches can grow
to nearly 8 inches (200 mm) in length. The majority of several hundred known species of