Wednesday, September 28, 2016

Giant Clam (Taklobo) - Threatened Marine Shellfish

Dr Abe V Rotor
Living with Nature School on Blog [ ]
Paaralang Bayan sa Himpapawid with Ms Melly C Tenorio 
738 DZRB AM Band, 8 to 9 evening class, Monday to Friday

On-site study. Author helps lift a taklobo specimen for study.

Seven-kilogram Tridacna is examined by students in Environmental Science from the UST Graduate School; bottom photo shows its natural habitat at 6 to 14 feet on coral reef of San Salvador Island, east of Masinloc, Zambales.

Facts about the giant clam, Tridacna gigas. 

1. In the Philippines it is called taklobo. It is the largest living bivalve mollusk and one of the most endangered clams.

2. It lives on shallow coral reefs of the South Pacific and Indian oceans, up to 20 meters deep.

3. It weighs more than 200 kilograms (440 pounds), and measures as much as 1.2 m (4 feet) across. It has an average lifespan in the wild of 100 years or more.

4. Although larval clams are planktonic, they become sessile in adulthood. Growth is enhanced by the clam's ability to grow algae in symbiosis. The creature's mantle tissues act as a habitat for the symbiotic single-celled dinoflagellate algae (zooxanthellae) from which it gets its nutrition. By day, the clam opens its shell and extends its mantle tissue so that the algae receive the sunlight they need to photosynthesize.

5. T. gigas reproduce sexually. They are hermaphrodites (producing both eggs and sperm), but self fertilization is not possible. Since giant clams can't move across the sea floor, the solution is broadcast spawning. This entails the release of sperm and eggs into the water where fertilization takes place.

Let's protect the giant clams. It's better to be assured they are alive on the seafloor than to have their fossils in our home.~

Tridacna in its natural habitat - lighted seafloor; Tridacna graveyard.

 Mrs Cecilia Rojas Rotor, author's wife. poses before a giant Tridacna 
shell as holy water receptacle. Mount Carmel Church, QC

References: Living with Nature by AVRotor; Marine Biology: An Ecological Approach by JW Nybakken; Wikipedia.

No comments: