DIVE DRY WITH DR. BILL #789: BUT ARE THEY ENERGY EFFICIENT?
A while back I focused several of my columns on our closest invertebrate relatives, the salps. The larvae of these critters have primitive nerve chords placing them in the Phylum Chordata along with humans, fish, marine mammals and the like. Salps are pelagic or open water critters that drift in the water column. However their close relatives known as tunicates or sea squirts aren't as adventurous and live their lives attached to the ocean floor or other hard substrate.
Today I'll talk... er, write... about one species of tunicate commonly found in our waters. I'm referring to the light bulb tunicate, Clavelina huntsmani. I live in California where energy conservation is widely practiced, but I don't have a clue what the energy efficiency of these light bulbs is. Of course they don't actually produce light, they just look like an old incandescent light bulb!
There is more than one species of light bulb tunicate in the world's oceans. In fact there are nearly 50 of them! Clavelina lepadiformis is found in the North Atlantic and has probably been more intensely studied. In fact the genus Clavelina was described back in 1816. Our local species wasn't even described scientifically until 1931. Clavelina huntsmani is known from British Columbia down into Baja California. They tend to frequent depths shallower than 100 feet and prefer vertical rock surfaces or overhangs exposed to currents which bring in food. There is also an undescribed species, Clavelina sp.on our coast.
This is a social rather than solitary species. The individuals, referred to as zooids, are initially attached to one another. Each one may grow to a length of about two inches. The outer sheath or tunic is translucent allowing one to see internal structures within the body. There are two distinct pink bands around the feeding structure known as the pharyngeal basket that look like a light bulb filament. One may also see an orange ovary surrounded by white testes. The elongated abdomen contains the esophagous, stomach and intestines as well as the heart. My abdomen contains relatively little intestine after three cancer surgeries!
One can hardly say that these tunicates munch. They are filter feeders which use two siphons to take in water and expel it after planktonic food and organic matter has been filtered out. The intake siphon is known as the buccal siphon and the excurrent one as the atrial siphon. Food is trapped on mucus sheaths on the sides of the pharynx, the cavity leading from the mouth to the digestive tract.
These tunicates are hermaphroditic, containing both reproductive organs. Some species self-fertilize (what fun is that?) while others cross-fertilize. Their larvae get their nourishment from the egg's yolk until they settle out and become adults. One source said that larvae are brooded at the base of the adult's tunic but that seems to contradict the previous information. Morris, Abbott and Haderlie's tome Intertidal Invertebrates of California states the larvae are brooded in the atrial siphon's cavity.
It appears that the adult light bulb tunicates live a relatively short time. New colonies are apparent in spring and early summer. However, by fall they start to degenerate and are often gone by late fall. This information comes from my marine biologist icon Edward "Doc" Ricketts of Cannery Row fame in his book Between Pacific Tides. I not only used that fantastic resource back in my Harvard daze, but also when I taught marine biology at the Toyon School and even today in my research.
© 2018 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: Colonies of the light bulb tunicate (left); tunicates showing feeding siphons and greater detail thanks to an image by Kevin Lee (check out Kevin's fantastic images at DiverKevin).
View attachment 490895
A while back I focused several of my columns on our closest invertebrate relatives, the salps. The larvae of these critters have primitive nerve chords placing them in the Phylum Chordata along with humans, fish, marine mammals and the like. Salps are pelagic or open water critters that drift in the water column. However their close relatives known as tunicates or sea squirts aren't as adventurous and live their lives attached to the ocean floor or other hard substrate.
Today I'll talk... er, write... about one species of tunicate commonly found in our waters. I'm referring to the light bulb tunicate, Clavelina huntsmani. I live in California where energy conservation is widely practiced, but I don't have a clue what the energy efficiency of these light bulbs is. Of course they don't actually produce light, they just look like an old incandescent light bulb!
There is more than one species of light bulb tunicate in the world's oceans. In fact there are nearly 50 of them! Clavelina lepadiformis is found in the North Atlantic and has probably been more intensely studied. In fact the genus Clavelina was described back in 1816. Our local species wasn't even described scientifically until 1931. Clavelina huntsmani is known from British Columbia down into Baja California. They tend to frequent depths shallower than 100 feet and prefer vertical rock surfaces or overhangs exposed to currents which bring in food. There is also an undescribed species, Clavelina sp.on our coast.
This is a social rather than solitary species. The individuals, referred to as zooids, are initially attached to one another. Each one may grow to a length of about two inches. The outer sheath or tunic is translucent allowing one to see internal structures within the body. There are two distinct pink bands around the feeding structure known as the pharyngeal basket that look like a light bulb filament. One may also see an orange ovary surrounded by white testes. The elongated abdomen contains the esophagous, stomach and intestines as well as the heart. My abdomen contains relatively little intestine after three cancer surgeries!
One can hardly say that these tunicates munch. They are filter feeders which use two siphons to take in water and expel it after planktonic food and organic matter has been filtered out. The intake siphon is known as the buccal siphon and the excurrent one as the atrial siphon. Food is trapped on mucus sheaths on the sides of the pharynx, the cavity leading from the mouth to the digestive tract.
These tunicates are hermaphroditic, containing both reproductive organs. Some species self-fertilize (what fun is that?) while others cross-fertilize. Their larvae get their nourishment from the egg's yolk until they settle out and become adults. One source said that larvae are brooded at the base of the adult's tunic but that seems to contradict the previous information. Morris, Abbott and Haderlie's tome Intertidal Invertebrates of California states the larvae are brooded in the atrial siphon's cavity.
It appears that the adult light bulb tunicates live a relatively short time. New colonies are apparent in spring and early summer. However, by fall they start to degenerate and are often gone by late fall. This information comes from my marine biologist icon Edward "Doc" Ricketts of Cannery Row fame in his book Between Pacific Tides. I not only used that fantastic resource back in my Harvard daze, but also when I taught marine biology at the Toyon School and even today in my research.
© 2018 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: Colonies of the light bulb tunicate (left); tunicates showing feeding siphons and greater detail thanks to an image by Kevin Lee (check out Kevin's fantastic images at DiverKevin).
View attachment 490895
