10 January 2010

Mud slinging mudskippers at Chek Jawa

There are lots of interesting mudskippers on Chek Jawa.
Today I noticed a Gold-spotted mudskipper (Periophthalmus chrysospilos) digging out a 'swimming pool'.

The fish excavates the burrow using only its mouth. It can spit balls of mud quite some distance from the burrow entrance!
Shortly after some spitting, this mudskipper waddled out and started to harass some crabs nearby. Raising its coulourful dorsal fins at the poor startled crab.
Then the bullying mudskipper noticed another mudskipper coming near its burrow. It immediately abandoned the crabs and hurried back to the burrow. Instead of trying to bite the intruder, it got into the burrow, then spat mud balls at the other mudskipper! Andy took a video of this and James has a great shot of it spitting out the mud on his blog post. Amazing!

We were also fascinated by the leaping mudskippers. These long skinny Bearded mudskippers (Scartelaos histophorus) literally stand on their tails to leap right out of the mud with pectoral fins spread out. Today I noticed that when doing the leap, the fish does not raise its skinny tall flag-like dorsal fin. But it does spread out the stretch of dorsal fin along the body length.
Here's a mudskipper landing at the end of its leap, with its long dorsal fin still spread out.
The fish only seems to use its skinny tall flag-like dorsal fin when it is not leaping. Although the long dorsal fin is also spread out when it is horizontal as well. James has lots of great photos of these fishes biting each others' tails and other strange poses on his blog post.
Also out on mudflats at the coastal boardwalk were other kinds of mudskippers. This largish one might be the Yellow spotted mudskipper (Periophthalmus walailakae)?
While this small one might be Dusky-gilled mudskipper (Periophthalmus novemradiatus)?
And this one is a Gold-spotted mudskipper (Periophthalmus chrysospilos) , not obsessed with a burrow. Perhaps a female?
In the back mangroves, I finally saw the pretty Blue-spotted mudskipper (Boleophthalmus boddarti).
But it wouldn't raise its pretty dorsal fin.
Also in the back mangroves were stoic and unmoving Giant mudskippers (Periophthalmodon schlosseri).
In its burrow dug out out in what seems to be rather hard mud, was this mudskipper. I don't know what it is.
There were more lively small mudskippers like this one which seems to be a Silver-lined mudskipper (Periophthalmus argentilineatus).
It skips too, but much more sedately compared to the 'dancing' Bearded mudskippers.
There was also this small mudskipper. I'm not sure what it is.
Wow, there's so much to see and learn, just looking at mudskippers at Chek Jawa!

By some coincidence, I just received an email from Wendy from Langkawi who blogs at Nature is Awesome. She said:

Someone asked me this interesting question and I thought I want to share this with you and your shore friends

All of us know that mudskippers belong to gobidae family, which is fish, right? They feed on mudflat while on land. On land, they are easy prey to kingfishers or herons. If that so, why must they spend so much time on land? Why can't they go deeper into the water and suck their mud at the bottom?

Hope someone have a better answer than to say "That's why they are mudskippers mah... and the work of evolution".

I'm not really sure myself. My guess is that being able to forage and frolick out of water gives mudskippers an advantage over other fishes who have to leave the mudflats at low tide. Perhaps to a clumsy mudskipper, marine predators are scarier than aerial ones? And for both kinds of predators, they can hide in the burrows that they build?

Any other information or guesses anyone?

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