DIVE DRY WITH DR. BILL #886: GOT THE COBALT BLUES AGAIN
Divers in warmer waters are familiar with large barrel sponges. Unfortunately the only ones in our waters seem to be at much deeper depths, and even though I'm a very "deep" person I no longer go there! We do have a number of sponge species in California, but most of them are small and more subtle. Many divers don't even know they are members of the phylum Porifera. One that does stand out, mainly due to its beautiful blue color, is the cobalt sponge (Acanthancora cyanocrypta).
Many may not recognize it as a sponge because it grows as a thin "sheet" a few millimeters thick on rocks and other hard surfaces. The tiny incurrent pores that intake water are visible only under a microscope (at least given my poor vision) and the excurrent pores are noticeable but very small. Like other sponges, these feed on organic matter and tiny plankton filtered out of the water column.
The beautiful blue color is unique among California sponges, but is not the color of the actual sponge. It derives from cyanobacteria (blue-green algae) that are embedded in its tissues. They are capable of photosynthesizing and their by-products include nutrients the sponge can utilize. In turn, they are given shelter by the sponge. I'm not aware of any predators on this species of sponge. Members of this species that lack the cyanobacteria are a light orange in color although I've never knowingly seen one.
According to Jensen, et al. Beneath Pacific Tides, the cobalt sponge ranges from British Columbia to Baja California. The ones I generally see are in shallow water but they can extend down to nearly 200 ft. I've never seen one that deep myself. Since light levels at such depths are low, perhaps this is where the photosynthetic cyanobacteria are absent and the sponges are orange in color.
Now one would not expect the sex life of a sponge to be very exciting... and they are right. However, members of the sponge class Demospongiae do have two modes of reproduction. They can do "it" both asexually and sexually. Asexual reproduction is accomplished by budding. In the sexual mode, fertilization occurs internally and the larvae are released into the water column.
© 2020 Dr. Bill Bushing. For the entire archived set of nearly 900 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Beautiful cobalt sponge encrustations on rock; close-up showing mini "eco-system" on sponge and enlargement of image by Kevin Lee showing tiny incurrent pores.
Divers in warmer waters are familiar with large barrel sponges. Unfortunately the only ones in our waters seem to be at much deeper depths, and even though I'm a very "deep" person I no longer go there! We do have a number of sponge species in California, but most of them are small and more subtle. Many divers don't even know they are members of the phylum Porifera. One that does stand out, mainly due to its beautiful blue color, is the cobalt sponge (Acanthancora cyanocrypta).
Many may not recognize it as a sponge because it grows as a thin "sheet" a few millimeters thick on rocks and other hard surfaces. The tiny incurrent pores that intake water are visible only under a microscope (at least given my poor vision) and the excurrent pores are noticeable but very small. Like other sponges, these feed on organic matter and tiny plankton filtered out of the water column.
The beautiful blue color is unique among California sponges, but is not the color of the actual sponge. It derives from cyanobacteria (blue-green algae) that are embedded in its tissues. They are capable of photosynthesizing and their by-products include nutrients the sponge can utilize. In turn, they are given shelter by the sponge. I'm not aware of any predators on this species of sponge. Members of this species that lack the cyanobacteria are a light orange in color although I've never knowingly seen one.
According to Jensen, et al. Beneath Pacific Tides, the cobalt sponge ranges from British Columbia to Baja California. The ones I generally see are in shallow water but they can extend down to nearly 200 ft. I've never seen one that deep myself. Since light levels at such depths are low, perhaps this is where the photosynthetic cyanobacteria are absent and the sponges are orange in color.
Now one would not expect the sex life of a sponge to be very exciting... and they are right. However, members of the sponge class Demospongiae do have two modes of reproduction. They can do "it" both asexually and sexually. Asexual reproduction is accomplished by budding. In the sexual mode, fertilization occurs internally and the larvae are released into the water column.
© 2020 Dr. Bill Bushing. For the entire archived set of nearly 900 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Beautiful cobalt sponge encrustations on rock; close-up showing mini "eco-system" on sponge and enlargement of image by Kevin Lee showing tiny incurrent pores.
