Megasiphon Thylacos, a new fossil species of tunicate discovered

Tags: Environment Science and Technology

Researchers recently described a new fossil species of tunicate called Megasiphon Thylacos

An Overview of the News

• The Megasiphon Thylacos fossil is about 500 million years old.

• The discovery suggests that the modern tunicate body plan was established shortly after the Cambrian explosion.

• The fossil provides insight into the sedentary, filter-feeding lifestyle of ancestral tunicates and their metamorphosis from tadpole-like larvae.

About Tunicates

• Tunicates, commonly known as sea squirts, are a group of marine animals.

• They spend most of their lives attached to surfaces such as docks, rocks or the bottom of a boat.

• There are about 3,000 species of tunicates in the world's oceans, mainly in shallow water habitats.

• The evolutionary history of tunicates dates back at least 500 million years.

Tunicate Lineage:

• Ascidians: Ascidians, often called "sea wasps", are one of the main tunicate lineages.

• They begin their lives as mobile, tadpole-like larvae.

• As they mature, they undergo metamorphosis and turn into barrel-shaped adults with two siphons.

• Ascidians spend their adult lives attached to the ocean floor.

• Appendicularians: The Appendicularias represent another Angrakha dynasty.

• They retain their tadpole-like appearance even when they become adults.

• They float freely in the upper water.

• They appear to be more distantly related to vertebrates than to ascidians.

Physical Characteristics and Feeding Mechanism:

• The body of adult tunicates is usually barrel-shaped.

• They have two siphons coming out of their body.

• A siphon draws water along with the food particles using suction.

• The other siphons the filtered water back out.