DIVE DRY WITH DR. BILL #797: THE GLASS IS DEEP
In the past I've been a pretty deep fellow, often diving to a depth of 200 fsw on air to film the unusual critters down there. Today I'm a much shallower guy, rarely venturing below 100 fsw on the days my cancer allows me to enter Neptune's realm. I recently had to rely on the movie "Aquaman" to see the denizens of the deep (although as an experienced marine biologist of many decades, most of the ones in the movie were fantasy).
I had heard from tech divers like Steve Millington that they had encountered sponges at depths below my limit, but I never saw one myself. Then a while back local instructor and friend Mark Guccione showed me a sponge that had been dredged from deep water by a fishing boat. I asked him to send me a few pictures so I could use them in this column.
Now sponges are benthic filter feeders living attached to the bottom (or hard shells and debris) that pass water through their simple bodies to extract food particles from it. We have several small shallow water sponges in our waters and on my international dive trips I've filmed ones that I could comfortably sit in. I sometimes feel pretty old these days (however young at heart), but sponges have been around for at least 600 million years.
Those that are found in deep water are different from the ones we encounter in shallower waters. They are usually "glass" sponges, with silicon based spicules forming the structure for their living cells. The spicules usually have six points and look something like the jacks we used to play with as kids (or that our parents stepped on when we left them on the floor... much more effective than Legos). The majority of shallow water sponges have soft structures made of spongin and are susceptible to predation. They often employ chemical defenses to ward off those who would choose to munch on them. It is these sponges (Demospongia) that have been used by humans for centuries. In my youth we had real sponges in the household but fortunately synthetic ones were created to eliminate the pressure on the living ones.
The deep water glass sponges (Hexactinellida) are not as vulnerable. They usually live at depths of 1,000 to 22,000 feet. There are far fewer sponge predators way down deep. Chowing down on "glass" doesn't sound very appetizing anyway, and these sponges do not need chemical defenses. They often form sponge "grounds" or reefs which have been studied off Washington and Oregon as well as other locations around the globe.
For those of you with a scientific bent (most biologists are a bit "bent" in my experience), many of the "cells" in glass sponges are unusual. The are in a condition referred to as syncytial. This means that instead of individual cells containing a nucleus and cell membrane, much of the soft portion of these sponges contains many nuclei and the cytoplasm (cell "contents") are amorphous and free to move about the sponge. Sounds a bit eery even to me, but life has many interesting mysteries.
Being very primitive as a group, sponges possess no real tissues... no digestive, nervous or circulatory systems. In my years I think I've met a small number of humans that may have evolved ditrectly from sponges (and I'm not referring to Sponge Bob). The glass sponges do have the ability to transmit electrical signals quickly and respond to external stimuli. I wish my local ISP would learn a lesson from them. Now simplicity may be a key to longevity. Glass sponges are long-lived with one estimated at 23,000 years old (although that has been disputed).
Now the sex life of sponges is not very interesting. It is almost as boring as mine. They are capable of asexual reproduction by budding or fragmentation. I am not. They may also reproduce sexually with sperm cast into the water to be received by female structures. I hope that satisfies those of my readers with prurient interests!
Although glass sponges, like their softer relatives, may be used to develop pharmaceuticals; humans rarely have contact with the living forms. I was suprised to discover during my research that in Japan they are given as wedding presents. Even if I marry a lovely lady diver from that country, I hope no one is inclined to do that for us.
© 2019 Dr. Bill Bushing. For the entire archived set of nearly 800 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Images of the deep water sponge taken by friend and local dive instructor Mark Guccione.
In the past I've been a pretty deep fellow, often diving to a depth of 200 fsw on air to film the unusual critters down there. Today I'm a much shallower guy, rarely venturing below 100 fsw on the days my cancer allows me to enter Neptune's realm. I recently had to rely on the movie "Aquaman" to see the denizens of the deep (although as an experienced marine biologist of many decades, most of the ones in the movie were fantasy).
I had heard from tech divers like Steve Millington that they had encountered sponges at depths below my limit, but I never saw one myself. Then a while back local instructor and friend Mark Guccione showed me a sponge that had been dredged from deep water by a fishing boat. I asked him to send me a few pictures so I could use them in this column.
Now sponges are benthic filter feeders living attached to the bottom (or hard shells and debris) that pass water through their simple bodies to extract food particles from it. We have several small shallow water sponges in our waters and on my international dive trips I've filmed ones that I could comfortably sit in. I sometimes feel pretty old these days (however young at heart), but sponges have been around for at least 600 million years.
Those that are found in deep water are different from the ones we encounter in shallower waters. They are usually "glass" sponges, with silicon based spicules forming the structure for their living cells. The spicules usually have six points and look something like the jacks we used to play with as kids (or that our parents stepped on when we left them on the floor... much more effective than Legos). The majority of shallow water sponges have soft structures made of spongin and are susceptible to predation. They often employ chemical defenses to ward off those who would choose to munch on them. It is these sponges (Demospongia) that have been used by humans for centuries. In my youth we had real sponges in the household but fortunately synthetic ones were created to eliminate the pressure on the living ones.
The deep water glass sponges (Hexactinellida) are not as vulnerable. They usually live at depths of 1,000 to 22,000 feet. There are far fewer sponge predators way down deep. Chowing down on "glass" doesn't sound very appetizing anyway, and these sponges do not need chemical defenses. They often form sponge "grounds" or reefs which have been studied off Washington and Oregon as well as other locations around the globe.
For those of you with a scientific bent (most biologists are a bit "bent" in my experience), many of the "cells" in glass sponges are unusual. The are in a condition referred to as syncytial. This means that instead of individual cells containing a nucleus and cell membrane, much of the soft portion of these sponges contains many nuclei and the cytoplasm (cell "contents") are amorphous and free to move about the sponge. Sounds a bit eery even to me, but life has many interesting mysteries.
Being very primitive as a group, sponges possess no real tissues... no digestive, nervous or circulatory systems. In my years I think I've met a small number of humans that may have evolved ditrectly from sponges (and I'm not referring to Sponge Bob). The glass sponges do have the ability to transmit electrical signals quickly and respond to external stimuli. I wish my local ISP would learn a lesson from them. Now simplicity may be a key to longevity. Glass sponges are long-lived with one estimated at 23,000 years old (although that has been disputed).
Now the sex life of sponges is not very interesting. It is almost as boring as mine. They are capable of asexual reproduction by budding or fragmentation. I am not. They may also reproduce sexually with sperm cast into the water to be received by female structures. I hope that satisfies those of my readers with prurient interests!
Although glass sponges, like their softer relatives, may be used to develop pharmaceuticals; humans rarely have contact with the living forms. I was suprised to discover during my research that in Japan they are given as wedding presents. Even if I marry a lovely lady diver from that country, I hope no one is inclined to do that for us.
© 2019 Dr. Bill Bushing. For the entire archived set of nearly 800 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Images of the deep water sponge taken by friend and local dive instructor Mark Guccione.
