Ceriagrion cerinorubellum; Agriocnemis femina; Lynx Spider

The world of insects is filled with peril as many of them are ferocious predators and it is really a survival of the fittest. A survey at Lorong Halus gave me an exciting insight into their prey-predator relationship.

Agriocnemis femina is a small damselfly measuring up to only about 17mm in body length. This species undergoes colour changes with maturity and mature males have a whitish synthorax. This dainty damselfly is common around ponds and drains and they share the same habitat with another damselfly species, Ceriagrion cerinorubellum.

C. cerinorubellum is about a size bigger than A. femina. They are fierce predators and it was not long before we chanced upon a C. cerinorubellum attacking and consuming an A. femina. The prey’s head had been consumed but we could clearly see that it was an immature male A. femina from the orange tip at the abdomen. The C. cerinorubellum was so engrossed on lunch that it simply ignored me as I approached it really close to get a clear picture.

In nature, it is a case of eat or be eaten. This time the predator became the prey. A Lynx Spider (Oxyopes sp.) had captured a C. cerinorubellum. Lynx Spiders have keen eyesight and they hunt down their prey with very agile movements. This individual must have sprung an ambush on C. cerinorubellum which did not stand a chance once the spider sank in its fangs.

As we were leaving Lorong Halus, C. cerinorubellum reminded us that it is still an awesome predator among the small invertebrates. I managed to record a video of one consuming a fly-like insect. I would imagine the chase prior to capture must be quite a dogfight, a battle for air supremacy on a miniature scale.

These little insects might not have the iconic status of lions or tigers. But they are just are vicious and ruthless when it comes to feeding time. I think back to the movie ‘Honey, I Shrunk the Kids’. With these fearsome insects around, that would be a real nightmare comes true.

Pictures and video taken at: Lorong Halus, November 2007.

References:

Koh, K. H. J., 1989. A Guide to Common Singapore Spiders. Singapore Science Centre.

Orr, A. G., 2005. Dragonflies of Peninsular Malaysia and Singapore, Natural History Publications (Borneo) Sdn. Bhd, Malaysia.

Stichopus herrmanni vs Stichopus chloronotus

The identity of the sea cucumber (see post) spotted at Pulau Semakau in August has finally been confirmed as Stichopus herrmanni. Below is the reply from Dr. Claude Massin from the Royal Belgian Institute of Natural Sciences in Belgium.

“Dear Colleague,

At first glance your specimen could be confused with a Stichopus chloronotus. However, if S. chloronotus has large dorsal papillae with orange tips, these papillae are always well aligned on rows. On your specimen, all the dorsal papillae have the same size and are evenly dispersed. This colour pattern is more reminiscent of S. herrmanni. Moreover, you have a lot of rosettes in your preparations. In S. chloronotus the rosettes are said to be absent or very rare. If you check the size of the C-shaped rods, it is also easy to separate S. chloronotus from S. herrmanni.

S. chloronotus: in dorsal body wall, maximum 45 µm long; in ventral body wall maximum 70 µm long.
S. herrmanni: in the dorsal body wall, 35-100 µm long; in the ventral body wall maximum 150 µm long.

I think your specimen is a particularly dark morph of S. herrmanni.”

Stichopus herrmanni (dark form)

Stichopus chloronotus

Stichopus herrmanni (greyish-green form)

In all the previous reference books and papers, pictures of S. herrmanni are always greyish-green or brownish-green in colour. Looks like we have observed a rather rare dark morph of this species.

Several studies on their reproductive cycle have been conducted in various parts of the world. In Iran, S. herrmanni spawn during the peak of summer in July-August while in New Caledonia, they spawn during the months of January-February. In both cases, warmer seawater temperature is the trigger for reproduction. I wonder what is the situation in Singapore where there is no significant seasonal climate differences in tropical Southeast Asia.

I’ve had the opportunity to interact with several echinoderm experts around the world and have gained much knowledge. I certainly look forward to more advice from them.


Pictures taken at: Pulau Semakau, August 2007; S. chloronotus and S. herrmanni (greyish-green form) are from the book Taxonomie des holothuries des Comores.

References:

Massin, C., Y. Zulfigar, A. S. H. Tan & S. Z. Rizal Boss, 2002. ‘The genus Stichopus (Echinodermata: Holothuroidea) from the Johore Marine Park (Malaysia) with the description of two new species’, Bulletin de l’Institut Royal des Sciences Naturelles de Belgique, Biologie, vol. 72, pp. 73-99.

Samyn, Y., D. VandenSpiegel & C. Massin, 2006. Taxonomie des holothuries des Comores, Abc Taxa (Volume 1), Belgium.

Tehranifard, A., S. Uryan, G. Vosoghi, S. M. Fatemy & A. Nikoyan, 2006. ‘Reproductive cycle of Stichopus herrmanni from Kish Island, Iran’, SPC Beche-de-mer Information Bulletin, vol. 24, pp. 22-27.