Polyplectana kefersteinii

I am now very intrigue by sea cucumbers. Everything about them fascinates me. Their docile nature belies a nasty defence mechanism; the myriad colours and sizes sea cucumbers can occur; they are not very well studied with many undescribe species and their overall squeamishness which, strangely, I find really appealing. And of course some of them really look like big poo.

There are about 1400 known species worldwide. They are classified into six orders and in total 25 families. I’ve so far seen representatives from five families on our intertidal shores. The latest is this one representing the synaptids.

A typical synaptid from the Order Apodida has no tube feet, has a very thin and sticky body wall and has no respiratory trees. Apodids’ oral tentacles can be simple or digitate or, like this individual has so beautifully demonstrated, feather-like.

This species is most probably a Polyplectana kefersteinii. But of course we would have to examine its microscopic ossicles to be 100% certain of the identification.

Picture and video taken at: A southern offshore island, March 2007 and Pulau Semakau, May 2007.


References:

Kerr, A. M., Holothuroidea. Sea cucumbers.
http://www.tolweb.org/Holothuroidea

Lane, D. J. W. & D. Vandenspiegel, 2003. A Guide to Sea Stars and other Echinoderms of Singapore, Singapore Science Centre, Singapore.

Ceriagrion cerinorubellum

Sex. What is your favourite position? For Odonates, it is the Wheel.

I spied this pair of Ceriagrion cerinorubellum damselfly in the heat of passion during my fieldwork. The female below had curled her abdomen towards the male’s genitalia to receive the sperm. And with that, the couple formed a beautiful heart shape wheel position. But all is not lovey dovey because the pair was engaged in a reproduction battle of wits.

The pair was locked in this position for almost 10 minutes. This long copulation period allows the male damselfly to remove rival sperm from the bursa copulatrix, a copulatory structure in the female. However in a classic case of cryptic female choice, the female retains control over reproduction as she can control the sperm reserves in her spermatheca. Knowing this, the male will prolong copulation to elicit the female to eject rival sperm and tempt her to use his sperm for fertilisation.

Thank goodness human reproduction is not this complicated.

C. cerinorubellum is a very common and colourful damselfly. They occur frequently in suburban gardens, drains and ponds. They are also vicious predators capable of tackling other damselfly species twice their size.

Colourful, ferocious and sexually competitive. Quite a character for a tiny insect!



Pictures taken at: A northern offshore island, March 2007 and western part of Singapore, February 2007.


References:

A. G. Orr., 2003. A Guide to the Dragonflies of Borneo. Their Identification and Biology, Natural History Publications (Borneo) Sdn. Bhd, Malaysia.

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

Uhia, E & A. C. Rivera, 2005. ‘Male damselflies detect female mating status: importance for postcopulatory sexual selection’, Animal Behaviour, vol. 69 (4), pp. 797-804.