Behaviour and life history of giant clams

I decided to dedicate a post to some of my giant clam work from the past two years. These works here have been published and have some interesting findings on the giant clams' ecology and behaviour...

Predator-induced changes in fluted giant clams (Tridacna squamosa) shell morphology. Journal of Experimental Marine Biology and Ecology.

Phenotypic plasticity refers to the adaptability of organisms to change their outward traits (i.e. phenotype) in response to changes in the environment or other abiotic factors. Here, we tested the effects of predator effluent (or juice) taken from a local crab species, and shower these juvenile clams with these juices at two different concentrations for 6 months! Imagine being subjected to a 'harsh' environment for 6 months, what will happen to you?

Using shell morphology traits, I measured these traits as shown in the figure above, and did an analysis on them. It turned out that clams subjected to 'fed crabs' treatment (meaning that the crab is well-fed on a regular basis) poses a higher risk to these clams, and they turned out smaller but slightly stronger in shell strength.

This study has a higher implication - these clams can adapt and change their shells in accordance to the environment. In the unpredictable and harsh ocean environment these days, phenotypic plasticity plays an important role to allow our marine organisms to rapidly adapt to these changes to maintain survival.

Quantification of water squirting by juvenile fluted giant clams (Tridacna squamosa L.). Journal of Ethology.

This is one interesting study that I'm very proud of - I designed this set up! hehe... Anyhow, this is a behaviour study that examines this squirting behaviour in juvenile giant clams. We know that giant clam adults are big and have few predators. But how about the babies? So this brings me to determining the strength of these squirts and whether they are strong enough to effect their potential predators. Early studies on squirting have suggested that it's a form of predator deterrence (especially the fishes).

In this tiny figure, (that I did up for my honours thesis) shows the several types of 'squirt' patterns that each generates. I did 54 trials and these are the preliminary results. In the paper, you can find more analysis and charts to show a strong positive correlation of increasing squirt strength with size. We infer that the force exerted by the squirt and after it is translated into 'underwater' squirt force (some physics equations to convert these values), the force becomes somewhat stronger and may possibly be a deterrence! Wow whee! :)


The implication of this study is basically useful as a background of nursery-size - how big the clams should be prior to restocking so that we can ensure high survivorship. :)

Most recently out online - finally after 3 years...


This article describes the early life history of the giant clams - how the tiny egg becomes a big clam... :) We also included an experiment in it to make it more complete. I basically followed the life stages and took photos of the process... The birth of life!



The paper includes the metamorphosis times for each stage or phase change. It was definitely really great fun to observe them so up-close.

I've been studying these giant clams for almost 5 years! And I still can think of many experiments and stuff to study about them. I hope that my upcoming works will be published soon and will continue to share about these amazing iconic invertebrates. Who ever says that clams are boring? :)