Ribbon Worms (phylum Nemertea) are soft-bodied, bilaterally symmetrical animals that are mostly long, thin and flat (like a ribbon). Some species, however, have short and wide bodies. They have an eversible proboscis (with either a sticky tip or tipped with a venomous stylet) which can shoot out just above the mouth to capture/retrieve their food. Carnivorous species are usually venomous, and use their venom to knock out or even kill their prey, which could be animals smaller or even as big as themselves. Others may be filter feeders, feeding on plankton. Ribbon worms respire through their skins. A number of species are known to be poisonous and some can even secrete toxins to deter predators.
Most species (except the freshwater species) have separate sexes, and can reproduce sexually. Fertilisation is done externally - some broadcast their eggs and sperms into surrounding waters, while others may lay the eggs in burrows or cocoons. Bigger species can usually reproduce asexually by breaking up and regenerating the lost parts, thus growing into new individuals from each broken fragments.
So far I still did not have the luck to see freshwater ribbon worms in Singapore, and hence will only highlight the marine ribbon worms and some of those which we thought are terrestrial ribbon worms.
Marine Ribbon Worms
The Five-lined Ribbon Worm (Baseodiscus quinquelineatus) is commonly seen in the region, usually with 5 distinctive black lines running along the back of the worm. It can sometimes be confused with another similar-looking species, Baseodiscus delineatus, which have numerous lines as well, but the lines are usually incomplete and broken in between, and there are usually several dark blotches on its back. Both worms can grow to about 1m long.
This long pinkish unknown ribbon worm is sometimes encountered on our sandy shores.
This long and slimy ribbon worm is occasionally seen with sand and other small particles stuck to the layer of mucus on its body. It lives in a burrow, which it retracts into when disturbed.
This small ribbon worm, sometimes called the Morton’s Smiling Worm (Prosadenoporus mortoni), is usually not more than a few mm wide. This worm has two pairs of black eyes, a smile-like marking on its front end, a dark green band along its back and a blunt tail. It inhabits rocky shores and preys on small invertebrates.
Most species (except the freshwater species) have separate sexes, and can reproduce sexually. Fertilisation is done externally - some broadcast their eggs and sperms into surrounding waters, while others may lay the eggs in burrows or cocoons. Bigger species can usually reproduce asexually by breaking up and regenerating the lost parts, thus growing into new individuals from each broken fragments.
So far I still did not have the luck to see freshwater ribbon worms in Singapore, and hence will only highlight the marine ribbon worms and some of those which we thought are terrestrial ribbon worms.
Marine Ribbon Worms
The Five-lined Ribbon Worm (Baseodiscus quinquelineatus) is commonly seen in the region, usually with 5 distinctive black lines running along the back of the worm. It can sometimes be confused with another similar-looking species, Baseodiscus delineatus, which have numerous lines as well, but the lines are usually incomplete and broken in between, and there are usually several dark blotches on its back. Both worms can grow to about 1m long.
This Red Gorgon Worm (Gorgonorhynchus sp.) is sometimes seen under rocks in intertidal areas. It has a sticky, branching proboscis that resembles the snake-covered heads of a Gorgon. The proboscis can be everted from a tiny hole above the mouth to capture small animals.
This long pinkish unknown ribbon worm is sometimes encountered on our sandy shores.
This long and slimy ribbon worm is occasionally seen with sand and other small particles stuck to the layer of mucus on its body. It lives in a burrow, which it retracts into when disturbed.
This small ribbon worm, sometimes called the Morton’s Smiling Worm (Prosadenoporus mortoni), is usually not more than a few mm wide. This worm has two pairs of black eyes, a smile-like marking on its front end, a dark green band along its back and a blunt tail. It inhabits rocky shores and preys on small invertebrates.
The above is a Mangrove Ribbon Worm (Pantinonemertes sp.), which is usually seen on mud lobster mound or under fallen logs. Like many ribbon worms, it has a long eversible proboscis which it uses to snare prey.
References
- Kuiter, R.H. and H. Debelius. 2009. World Atlas of Marine Fauna. IKAN-Unterwasserachiv. 723 pp.
- Ruppert, E.E. and R.D. Barnes. 1991. Invertebrate Zoology (International Edition). Saunders College Publishing. U.S.A. 1056 pp.
- Allen, G.R. and R. Steene. 2002. Indo-Pacific Coral Reef Field Guide. Tropical Reef Research. 378 pp.
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