28 March 2009

Spider hunting at Sungei Buloh

Volunteers gathered early this morning at Sungei Buloh to help out at the spider survey organised by Mendis.How fortunate we are to have David Court with us. He not only patiently explained interesting aspects of spiders, but also found lots of spiders and other insects!

He found this gorgeous Lacewing (Order Neuroptera). While the adults are pretty little things, the larvae can be voracious predators. Some familiar animals that belong to this order include antlions, which build conical traps in fine sand and wait at the base for hapless creatures to stumble in.We also saw the beautiful Mangrove St. Andrews' Cross spider (Argiope mangal) which was described by Joseph Koh in 1991 from specimens from Lim Chu Kang! (See his paper "Spiders of the Family Araneidae in Singapore mangroves" in the Raffles Bulletin of Zoology; download PDF). It is different from Argiope versicolor.

In the Mosquito Valley of Buloh, we saw lots of other spiders like Beccari's Tent Spider (Cyrtophora beccarii), Red Tent Spider (Cyrtophora unicolor), the Batik Golden Web Spider (Nephila antipodiana) and a Portia. But I scurried away to the Mangrove Arboretum, a lovely boardwalk through lush mangroves. The plants sure have grown since I last visited some years ago.Here we look at some lovely flowering mangrove plants (there were so many I made a separate post), and David found MORE spiders.This is the Mangrove Big-Jawed Spider (Tetragnatha josephi) in its web. This spider was named after Joseph Koh! These spiders have very long legs and are equipped with well developed jaws. The jaws of the male are particularly elongated and are equipped with a spur each. These are instrumental in locking the jaws of the female during mating.And a pair of these spiders were found on a leaf that was laced with silk. Is some jaw locking about to take place?On a nearby leaf was another spider alone with one leg on what looks like an egg sac. Is it a female guarding her eggs? There's a lot more to learn about our spiders!Another member of the family of big-jawed spiders (Family Tetragnathidae) is this colourful Leucauge sp. They build orb-webs on an inclined plane with an open hub.David also spotted this large but well camouflaged Ornamental Tree-Trunk Spider (Herennia ornatissima)! The female builds an orb-web that is only a few millimetres from the trunk and sits in a silken cup spun in or near the centre of the web.Another find by David is the Ant-Like Crab Spider (Amyciaea lineatipes). This spider not only mimics the fiercely biting Weaver ants (Oecophylla smaragdina), but also eats these ants! When it catches an ant, it drops off on a silken line with its prey to safely wait for the hapless ant to succumb to the spider's venom. David notices tiny flies around the ant! I only saw the flies after I took the photo. Wow!We also saw lots of other interesting insects like this pretty yellow dragonfly.And this dragonfly with black and yellow markings on its wings. When I first saw one flying about, I thought it was a bee!And an elegant damselfly. And while I was trying to photograph these flowers, a little wasp-like creature with a bright yellow head and thick yellow antennae poked its head into the flowers. I have no idea what all these insects are!
As we wandered along the Arboretum, the tide was coming in.
And lots and lots of different kinds of crabs were scuttling around the trees!There were big squarish Tree climbing crabs (Episesarma sp.) And little Face-band sesarmine crabs (Perisesarma sp.). As well as countless tiny little crabs bubbling all over the mud.

We redouble our efforts to find the Hairy foot mangrove spider (Idioctis littoralis) which builds burrows with a trapdoor in mudlobster mounds in this area.Mendis and David have a look at some mounds near the boardwalk.
I also went down to have a look but failed to find any. Instead, I saw these Chut-chut snails (Cerithidea obtusa). Some had grey bodies like the one above.
Others had reddish bodies. One of the Malay names for this snail includes 'Mata merah' which means 'red eyes'. The living snail does indeed have red eyes!

David and Mendis have more luck and find signs of the trapdoor spider! Mendis found a door, but couldn't open it. The spider may be clinging on to it for dear life!David found an abandoned burrow and takes a closer look at the contents. Murder had obviously been done, but who did it? It's Mangrove CSI! These spiders are often parasitised by wasps, who lay their eggs on the paralysed spider.

As we ended our walk, it started to thunder and then rain. We hurried back just in time to avoid the downpour.Back in the dry and warm office, Mendis shows us a video he took of Hairy foot mangrove spider.
Wow, that's really cool. It sure is hairy footed!We had a lovely lunch and spent time catching up. By which time the weather was warm and sunny again. It's great to have this opportunity to revisit one of my favourite wild places, with such enjoyable companions and have so many interesting encounters.

More about the blooming mangrove plants I saw today.

More about Sungei Buloh on the wildsingapore website and SBWR website.
See also the online "A Guide to Common Singapore Spiders" by Joseph K H Koh

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