DIVE DRY WITH DR. BILL #831: I THOUGHT INVERTEBRATES WERE SPINELESS!
I've been editing my video footage of the fish I filmed in the Philippines to create yet another of my glorious BluRay dive travelogues. I had so much footage from the 60 dives during that trip, that I had to separate the fish and invertebrates into two separate videos.
Thinking back to that trip, there were two critters that posed slight danger to this intrepid diver... the Titan triggerfish and several species of sea urchin! I never saw a single shark at Anilao or Puerto Galera so they were hardly an issue. The triggers would attack if one swam over the "funnel" above their nests. The sea urchins were a different story. On our night dives I would frequently get "stabbed" by their spines, sometimes with rather painful results.
There are several species of sea urchin there. They include the variable fire urchin (Asthenosoma varium), radiant sea urchin (Astropyga radiata) and black longspine urchin (Diadema setosum). The last two are members of the diadematoid urchins similar to the ones that James Bond had to pull the spines out of lovely Domino's foot. I should be so lucky.
The variable fire urchin is, as its name suggests, variable in coloration although the flesh covering its test is usually reddish. The dense cluster of spines are venomous and pack quite a wallop (as I discovered). They reach nearly 9" in diameter. The species is found from the Red Sea to Australia and north to Japan on sandy or rubble strewn bottoms. They feed on algae, seaweed and detritus with an occasional critter thrown in for protein. Coleman shrimp (Periclimenes colemani) are often found in association with them.
The radiant sea urchin is a beauty... but a dangerous one. Its spines are also venomous, and it inflicted a number of assaults through my 3mm wetsuit. There are clusters of deep red to yellowish spines separated by open areas with a central row of neon blue spots.It comes out mostly at night, which is when I got stabbed. The species is known from the east coast of Africa to Australia and Hawaii. They graze on algae. The radiant urchin is light-sensitive and will direct its spines toward any threat (like me?). It also has several shrimp and crab species associated with it and the young of some fish will seek protection near its spines.
The black longspined urchin's lengthy spines can easily penetrate both wetsuit and flesh, and may break off and become embedded. They are only mildly venomous but their length makes them an effective defense. This species tends to prefer muddy bottoms. It feeds on algae that grow on dead coral or rubble.
Urchins have separate sexes. I'm afraid their love life is barely worthy of a mention (just like mine). They cast sperm and eggs into the surrounding water and hope for a lottery win. Some urchins will brood their eggs on their dorsal surfaces. The larvae drift in the plankton until they are ready to settle down.
These were not the only sea urchins I encountered in the Philippines. I also saw and filmed cake (Tripneustes gratilla), occasionally covered with trash for "camouflage;" double spined (Echinothrix calamaris) with banded spines; and heart urchins (species uncertain). However all these species were well-behaved and left the good doctor alone!
© 2019 Dr. Bill Bushing. For the entire archived set of over 800 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Radiant urchin and one with spines erect for defense; variable urchin and longspined urchins gathered to "attack" me!
I've been editing my video footage of the fish I filmed in the Philippines to create yet another of my glorious BluRay dive travelogues. I had so much footage from the 60 dives during that trip, that I had to separate the fish and invertebrates into two separate videos.
Thinking back to that trip, there were two critters that posed slight danger to this intrepid diver... the Titan triggerfish and several species of sea urchin! I never saw a single shark at Anilao or Puerto Galera so they were hardly an issue. The triggers would attack if one swam over the "funnel" above their nests. The sea urchins were a different story. On our night dives I would frequently get "stabbed" by their spines, sometimes with rather painful results.
There are several species of sea urchin there. They include the variable fire urchin (Asthenosoma varium), radiant sea urchin (Astropyga radiata) and black longspine urchin (Diadema setosum). The last two are members of the diadematoid urchins similar to the ones that James Bond had to pull the spines out of lovely Domino's foot. I should be so lucky.
The variable fire urchin is, as its name suggests, variable in coloration although the flesh covering its test is usually reddish. The dense cluster of spines are venomous and pack quite a wallop (as I discovered). They reach nearly 9" in diameter. The species is found from the Red Sea to Australia and north to Japan on sandy or rubble strewn bottoms. They feed on algae, seaweed and detritus with an occasional critter thrown in for protein. Coleman shrimp (Periclimenes colemani) are often found in association with them.
The radiant sea urchin is a beauty... but a dangerous one. Its spines are also venomous, and it inflicted a number of assaults through my 3mm wetsuit. There are clusters of deep red to yellowish spines separated by open areas with a central row of neon blue spots.It comes out mostly at night, which is when I got stabbed. The species is known from the east coast of Africa to Australia and Hawaii. They graze on algae. The radiant urchin is light-sensitive and will direct its spines toward any threat (like me?). It also has several shrimp and crab species associated with it and the young of some fish will seek protection near its spines.
The black longspined urchin's lengthy spines can easily penetrate both wetsuit and flesh, and may break off and become embedded. They are only mildly venomous but their length makes them an effective defense. This species tends to prefer muddy bottoms. It feeds on algae that grow on dead coral or rubble.
Urchins have separate sexes. I'm afraid their love life is barely worthy of a mention (just like mine). They cast sperm and eggs into the surrounding water and hope for a lottery win. Some urchins will brood their eggs on their dorsal surfaces. The larvae drift in the plankton until they are ready to settle down.
These were not the only sea urchins I encountered in the Philippines. I also saw and filmed cake (Tripneustes gratilla), occasionally covered with trash for "camouflage;" double spined (Echinothrix calamaris) with banded spines; and heart urchins (species uncertain). However all these species were well-behaved and left the good doctor alone!
© 2019 Dr. Bill Bushing. For the entire archived set of over 800 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Radiant urchin and one with spines erect for defense; variable urchin and longspined urchins gathered to "attack" me!
