Saturday 14 September 2019

123 — Ribbon worms (Nemertea)

Nemerteans (or ribbon worms) are long thin slender worm-like animals. They can be found in marine, fresh water, and terrestrial environments, although they are far more diverse in the marine realm. In some ways they are not the most charismatic of groups, being worm-like in form, but they are often brightly coloured. Most species are also quite small (to ~10cm), but one Norwegian species (Lineus longissimus (Gunnerus, 1770)) can attain an almost unbelievable 50m in length and is the longest animal on Earth (Göransson, et al., 2019).

Purple nemertean, low tide, under a stone,
Pilot Bay, Mt. Maunganui, 25/12/19.
The same nemertean as above.
Orange nemertean, Tamaki Drive, Auckland.
Orange nemertean, low tide, North Piha,
west Auckland, 27/04/17
Nemerteans occupy an enigmatic role in New Zealand marine ecosystems, mostly because they aren't well studied. Not not much seems to be known regarding the ecology of most New Zealand species. Some species have yet to be described, and for others their description is all that’s known (e.g., Cook, 2010). A brief scan of local literature (mostly biodiversity surveys) revealed that nemerteans were only differentiated by their colour (e.g., Taylor & Morrison, 2008).

Elsewhere, nemerteans are thought to be carnivores and/or scavengers. The larger ones move through peristaltic movements of their body wall muscles—this is shown quite nicely in the two video clips. When they encounter potential food/prey they can rapidly evert a long proboscis. The proboscis is used to immobilise the prey with toxins. These toxins are thought to have medical potential (von Remont, et al., 2014; Göransson, et al., 2019).

These video clips are of a nemertean found under a stone in Pilot Bay, Mt. Maunganui during 2018. The species is similar to the undescribed species shown by Cook (2010) on p281.



More info:

Cook, S. (2010). New Zealand Coastal Invertebrates, Canterbury University Press.

Göransson, U., Jacobsson, E., Strand, M., Andersson, H. K. (2019). The toxins of nemertean worms. Toxins, 11, 1–36.

Taylor, R. B., Morrison, A. (2008). Soft-sediment habitats and fauna of Omaha Bay, northeastern New Zealand. Journal of the Royal Society of New Zealand, 38(3), 187–214.

von Reumont, B. J., Campbell, L. I., Jenner, R. A. (2014). Quo Vadis Venomics? A Roadmap to Neglected Venomous Invertebrates. Toxins, 6, 3488–3551.

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