Jul 22, 2005

Snap, Crackle n Pop!


The last training session for new ReefWalk guides saw 13 enthusiastic individuals come forward, ready & willing to take on the same journey as I did from blur sotong to somewhat full-fledged guide. The new guides posed many questions, some of which baffled even the seasoned guides like MS & Pam, and most of which left me lagi blur, but also even more eager to quench my thirst for knowledge.


One of the questions posed was, "What's the difference between Snapping Shrimps and Pistol Shrimps?" Ok ok, it's not as difficult a question as "Do I look fat in this?"... But I didn't have a proper scientific answer to this so here it is now.

Snapping shrimps and pistol shrimps are the same if we're referring to all shrimps belonging to the family Alpheidae (more common on our shores fall under the genera Alpheus and Synalpheus). It's just that certain species are known as snapping n some pistol (Eg. Alpheus randalli - Randall's pistol shrimp; Alpheus bellelus - Pretty snapping shrimp).

Like you say "to-mah-to", I say "to-may-to" lah. Or like how some say Mermaid's fan, some say Mermaid's ear, some just say Padina seaweed. Of course, if you're already a bio major and can speak scientific gibberish like a 2nd language then you're probably cringing at the way I tend to generalise these dudes. But hey, sometimes one species is just a spot or stripe different from the next species, so give us "non-purists" a break!

Mermaid's Fan, a.k.a. Mermaid's Ear, a.k.a. Padina sp.

Apart from their "affair" with gobies (you should know this by now), here's more info about this "kow peh" fella for those who wanna know more: Snapping shrimp (Alpheus sp. or Synalpheus sp.) a.k.a. Pistol shrimp (other common names include Popping shrimp, Click shrimp, Symbiotic shrimp) is a finger-size shrimp with one oversized claw that resembles a boxing glove, that it uses to stun its prey by snapping the claw shut. The snapping produces a sharp cracking sound.

Extracted from: Roach, J. (2001), Snapping Shrimp Stun Prey with Flashy Bang, National Geographic News:

When colonies of the shrimp snap their claws, the cacophony is so intense that submarines can take advantage of it to hide from sonar!

The sound is caused by the bursting of a bubble that forms when a shrimp snaps its claw shut. The bubble emits not only sound but a flash of light, indicating the extreme temperature and pressure inside the bubbles before they burst. The stunning snap comes not from the clap of the claws coming together but from a bubble generated by the claws' rapid closing motion. When the claw snaps shut, a jet of water shoots out from a socket in the claw at speeds of up to 100 kilometers an hour, generating a low-pressure bubble in its wake. As the pressure stabilizes, the bubble collapses with a loud bang.

The whole process occurs within 300 microseconds! Using a device that counts photons, researchers have recorded that a flash of light also occurs when the bubble collapses. This emission of light suggests that the temperature inside the bubbles must be at least 5,000 degrees Kelvin (8,540 degrees Fahrenheit) at the time of collapse.

The flashing phenomenon is thought to be similar to sonoluminescence, in which bubbles that are in a liquid driven by a strong sound field emit light. Researchers have termed this shrimp activity shrimpoluminescence.

All this talk about prawns is making me long for my favourite "ha-meen" & "Hong Kong chee-cheong-fun" from K.L..... Sigh... Home food beckons.....

4 comments:

kilbunny said...

the mermaid's ears/ mermaid's fan thing can cause me to pull my hair out sometimes. especially when i say 'fans' first, then later say 'ears' coz of some @%@#! slip of the tongue, some smart-alec kid in the group would quickly point it out. "no no, fans!" AIYO. mermaid got no fan use ears lor. WHAT mermaids anyway? all dugongs anyway. haha.
btw, does anyone notice those nice moulds of sand we keep seein in the kusu lagoon? anyone knows what they are? i've been getting tons of questions, but yet to find out. definitely not sand collar i'm sure.

greengardn said...

Hmmm... If it's "poopie"-lookin' coils of sand then that would be the cast of an acorn worm. Plain mounds of sand, usually dug up by crabs I guess...

pammy whammy said...

hmmm got pictures... safe us from guessing... kekeke... could be er... crabs or worms ... depending on how big are the heaps of sand... :P

kilbunny said...

ah, not acorn worm poopies i'm sure. those r quite small. these sand moulds are about 30cm in diameter. or larger. i'll get a picture of it next reefwalk. :)