Marine Worms Spends Larval Phase As Transparent 'Swimming Head'

Nature always follows a unique path when it comes to animal development. Animals like mammals are expected to undergo changes as they grow up. Despite the changes that happen in their physical appearances, their main biological setup remains the same.

However, this is not the case for amphibians and insects. They first develop as larvae which are different from adult individuals. Then, they undergo metamorphosis to show their final form. Biologists have studied this process of development.

According to Stanford New Service, research animals which are commonly found in laboratories like mice, worm C. Elegans, and zebrafish are considered as direct developers because they don't undergo a larval stage.

Paul Gonzales from Stanford University's Hopkins Marine Station became a hunter, breeder, and a farmer or rare marine worms to fill in the gap in people's understanding of animal development. Gonzales believes that there are animals that undergo a long larval stage - a developmental strategy known as indirect development. And there is a big possibility that rare worms would help him to understand the process better.

Gonzales and his team discovered that worms go through a prolonged phase with little more than the head. According to the study published in Current Biology, many animals in the ocean shares this trunk-less stage and may even shed light on the biological development of early animals.

What Gonzalez and his colleagues found was that the worms go through a prolonged phase with little more than the head. This work, published in the Dec. 8 issue of Current Biology, suggests that many animals in the ocean likely share this trunk-less stage and it may even shed light on the biological development of early animals.

Genes which are linked to trunk development were switched off during the larval phase before the metamorphosis stage. But what happen is that most of the genes switched on are commonly associated with head development.

The larvae are hatch from eggs and are laid on the mud. And when the tide rises, the squishy, gel-filled animals will use their hairlike cilia to swim upwards and devour some algae. According to Gonzales, being balloon-shaped noggins rather than wriggling noodles can help the organisms float and feed themselves efficiently.