The Tube Worms
by: James W. Fatherree, M.Sc.
Tube worms are just that - a variety of marine worms that live in tubes. Most of them belong to one of two large groups, which are called sabellids and serpulids, and some specimens from each of these groups can be found regularly in aquarium shops. However, as neat looking and interesting as they are, they are definitely not for everyone.
The sabellid worms form a tube made of a tough but flexible material, which is sometimes coated with a layer of detritus, mud, sand, and/or small shell fragments, while the serpulids build rock-hard tubes made of calcium carbonate. Many of the "hard-tube" serpulids also produce a small plug or door-like structure, called an operculum, that they can use to seal themselves inside their tube, while the "soft-tube" sabellids do not. There are a few exceptions, but these are the general characteristics.
All of these worms also have specialized structures called crowns, which are extended from the tubes to collect food particles and for gas exchange. They act like a sieve and a gill at the same time. The typically circular-shaped crowns are made up of many branches called radioles, and the radioles themselves are covered by tiny hair-like branches. Thus, many look like some sort of small fan or feather duster.
As I said, the crowns capture food, and how they do it is quite interesting. The lower surface of each radiole is covered by tiny hair-like cilia that rhythmically move in such a way as to create water currents which move from the underside of the crown, upwards through the radioles, and away from the worm. Conversely, the upper side of each radiole has a series of grooves running down the middle from the tips to the center of the crown. So, the neat part is that when the bottom to top current is produced, small particles in the water are caught in eddies created on the upper side of the radioles and are caught and moved to the worm's mouth by more cilia the grooves. The cilia/grooves also sort the particles before sending them to the mouth, and any particles that are made of the wrong stuff, are too big, or are too small are rejected.
In addition, as they grow they tend to prefer different particle sizes. Very young, small worms have very small crowns/radioles/grooves and therefore prefer to capture and eat very small particles, like bacteria and single-celled phytoplankton. Conversely, big adult worms have bigger crowns/radioles/grooves and may feed exclusively on much, much larger multi-cellular zooplankton (still pretty small stuff, really). And, as you can guess, the preferred food size can depend on what maximum size an adult achieves. Tube worms can be very picky eaters!
Some Common Types: So, let's take a look at some of the common types of tube worms. There are lots and lots of little oddballs that show up in stores here and there, and many, many others that hitchhike on corals and live rock, but these are the four "regulars" you'll most often see for sale.
Feather dusters:
There are several relatively large sabellid tube worms called feather dusters, but Sabellastarte magnifica and spectabilis are the most common. They look so much alike that you can't ID them without removing one from its tube, but if you really want to know what you have the easy way to find out is to ask where it came from. S. magnifica is collected in the Caribbean, while S. spectabilis comes from the Indo-Pacific.
These two species' tubes may be 8 inches long and the worms have impressive crowns that are often 3 or 4 inches in diameter and nicely colored. Also note that the tubes are coated with mud/detritus particles, but not sand or other larger particles. These are indeed the most commonly offered tube worms by far and you will see them regularly at stores. This does not mean they are inherently hardy though, as they still require very fine foods despite their size.
Cluster dusters:
Cluster dusters, primarily the Caribbean Bispira brunnea, are much smaller sabellids. They have soft tubes that are typically only a couple of inches long at most, and their crowns may be less than a half-inch in diameter when full-grown. But, they are very attractive nonetheless, and typically come in tightly spaced clumps made up of numerous individuals.
Oddly enough, these worms can reproduce asexually (as can many others), and if conditions are optimal they may increase their numbers rapidly. But, in most cases they are rather difficult to keep alive long-term at all, so hoping for them to spread may be overly optimistic for most hobbyists.
Christmas trees worms:
The serpulid Christmas tree worms, Spirobranchus spp., are quite unusual in that you're likely to only see them living in colonies of stony corals. And when I say "in" I mean they settle on corals when they are larvae and then their hard tubes are actually covered over by coral skeleton as the coral grows. Thus, the worm's tube becomes integrated with the coral. They really do live in the coral colony, which is most often Porites.
Their tubes, which typically coil in spirals, can be 3 inches or so in total length, and their unique crowns can be close to an inch at full size. I say these are unique because they spiral upwards from a wide base to a small tip in a corkscrew fashion, and are found in distinct pairs extended from the tube. Unlike the typical feather duster look, these crowns really look like two small trees, and come in all sorts of bright colors and neat patterns.
These used to be very common back in the "old days" when non-aquacultured Florida live rock was available, as they were often present on pieces of "wild" rock. But, now you can't get that type of rock and pretty much have to buy a coral to get the worms (which are coming from the Indo-Pacific). Thus, you'll have to make sure you can care for the worms properly - and the living coral, too. These are therefore suitable for reef-aquariums only!
Cocoa worms:
The Indo-Pacific serpulid cocoa worm, Protula bispiralis, which is also often called the "hard-tube worm", is another big and beautiful tube worm. These may have a tube that is over a foot long and an inch in diameter, and they also have two typically brightly-colored crowns. The crowns are also tiered, and look more like those of the Christmas tree worms than the sabellid feather and cluster dusters.
They are seen with some regularity in stores, but unfortunately they are probably the least likely to survive for long. Again, despite their larger size, they'll require fine foods that are typically in short supply in most aquariums. Even in well-maintained reef aquariums these worms infrequently live more than a few months.
(CONT)
by: James W. Fatherree, M.Sc.
Tube worms are just that - a variety of marine worms that live in tubes. Most of them belong to one of two large groups, which are called sabellids and serpulids, and some specimens from each of these groups can be found regularly in aquarium shops. However, as neat looking and interesting as they are, they are definitely not for everyone.
The sabellid worms form a tube made of a tough but flexible material, which is sometimes coated with a layer of detritus, mud, sand, and/or small shell fragments, while the serpulids build rock-hard tubes made of calcium carbonate. Many of the "hard-tube" serpulids also produce a small plug or door-like structure, called an operculum, that they can use to seal themselves inside their tube, while the "soft-tube" sabellids do not. There are a few exceptions, but these are the general characteristics.
All of these worms also have specialized structures called crowns, which are extended from the tubes to collect food particles and for gas exchange. They act like a sieve and a gill at the same time. The typically circular-shaped crowns are made up of many branches called radioles, and the radioles themselves are covered by tiny hair-like branches. Thus, many look like some sort of small fan or feather duster.
As I said, the crowns capture food, and how they do it is quite interesting. The lower surface of each radiole is covered by tiny hair-like cilia that rhythmically move in such a way as to create water currents which move from the underside of the crown, upwards through the radioles, and away from the worm. Conversely, the upper side of each radiole has a series of grooves running down the middle from the tips to the center of the crown. So, the neat part is that when the bottom to top current is produced, small particles in the water are caught in eddies created on the upper side of the radioles and are caught and moved to the worm's mouth by more cilia the grooves. The cilia/grooves also sort the particles before sending them to the mouth, and any particles that are made of the wrong stuff, are too big, or are too small are rejected.
In addition, as they grow they tend to prefer different particle sizes. Very young, small worms have very small crowns/radioles/grooves and therefore prefer to capture and eat very small particles, like bacteria and single-celled phytoplankton. Conversely, big adult worms have bigger crowns/radioles/grooves and may feed exclusively on much, much larger multi-cellular zooplankton (still pretty small stuff, really). And, as you can guess, the preferred food size can depend on what maximum size an adult achieves. Tube worms can be very picky eaters!
Some Common Types: So, let's take a look at some of the common types of tube worms. There are lots and lots of little oddballs that show up in stores here and there, and many, many others that hitchhike on corals and live rock, but these are the four "regulars" you'll most often see for sale.
Feather dusters:
There are several relatively large sabellid tube worms called feather dusters, but Sabellastarte magnifica and spectabilis are the most common. They look so much alike that you can't ID them without removing one from its tube, but if you really want to know what you have the easy way to find out is to ask where it came from. S. magnifica is collected in the Caribbean, while S. spectabilis comes from the Indo-Pacific.
These two species' tubes may be 8 inches long and the worms have impressive crowns that are often 3 or 4 inches in diameter and nicely colored. Also note that the tubes are coated with mud/detritus particles, but not sand or other larger particles. These are indeed the most commonly offered tube worms by far and you will see them regularly at stores. This does not mean they are inherently hardy though, as they still require very fine foods despite their size.
Cluster dusters:
Cluster dusters, primarily the Caribbean Bispira brunnea, are much smaller sabellids. They have soft tubes that are typically only a couple of inches long at most, and their crowns may be less than a half-inch in diameter when full-grown. But, they are very attractive nonetheless, and typically come in tightly spaced clumps made up of numerous individuals.
Oddly enough, these worms can reproduce asexually (as can many others), and if conditions are optimal they may increase their numbers rapidly. But, in most cases they are rather difficult to keep alive long-term at all, so hoping for them to spread may be overly optimistic for most hobbyists.
Christmas trees worms:
The serpulid Christmas tree worms, Spirobranchus spp., are quite unusual in that you're likely to only see them living in colonies of stony corals. And when I say "in" I mean they settle on corals when they are larvae and then their hard tubes are actually covered over by coral skeleton as the coral grows. Thus, the worm's tube becomes integrated with the coral. They really do live in the coral colony, which is most often Porites.
Their tubes, which typically coil in spirals, can be 3 inches or so in total length, and their unique crowns can be close to an inch at full size. I say these are unique because they spiral upwards from a wide base to a small tip in a corkscrew fashion, and are found in distinct pairs extended from the tube. Unlike the typical feather duster look, these crowns really look like two small trees, and come in all sorts of bright colors and neat patterns.
These used to be very common back in the "old days" when non-aquacultured Florida live rock was available, as they were often present on pieces of "wild" rock. But, now you can't get that type of rock and pretty much have to buy a coral to get the worms (which are coming from the Indo-Pacific). Thus, you'll have to make sure you can care for the worms properly - and the living coral, too. These are therefore suitable for reef-aquariums only!
Cocoa worms:
The Indo-Pacific serpulid cocoa worm, Protula bispiralis, which is also often called the "hard-tube worm", is another big and beautiful tube worm. These may have a tube that is over a foot long and an inch in diameter, and they also have two typically brightly-colored crowns. The crowns are also tiered, and look more like those of the Christmas tree worms than the sabellid feather and cluster dusters.
They are seen with some regularity in stores, but unfortunately they are probably the least likely to survive for long. Again, despite their larger size, they'll require fine foods that are typically in short supply in most aquariums. Even in well-maintained reef aquariums these worms infrequently live more than a few months.
(CONT)
