Tunicates

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Context

• A 500-million-year-old tunicate fossil species is recently described by researchers.
• For now it is concluded that after Cambrian Explosion the modern tunicate body was established and the species observed a dramatic rise in its population on earth.

Tunicates

• These are marine invertebrate species belonging to subphylum Tunicata.
• A total of 3,000 species of tunicates are believed to have existed in the oceans of this planet.
• Their body structure is sac or barrel like with two siphons, a tubular opening.
• These siphons are used to draw and expel water, filtration of water and also help in feeding.
• Though this species is invertebrate, these are considered as closest relatives of vertebrates such as fish, mammals, and people, and are connected through a tadpole-like link.
• They have evolutionary history going as back as 500 million years

Lineages – mainly 2 types

• Ascidiaceans –
  • These are most occurring type and are commonly referred as sea squirts.
  • In the beginning, these look like tadpoles and are mobile, which eventually developed to a barrel-shaped adult
  • These mostly spent their adult life attached to the seafloor.
• Appendicularias –
  • These look like tadpoles in both the phases of life- in the beginning and when they developed as adults.
  • They are not attached to seafloor their whole life and can swim freely in the upper waters.

Significance of Tunicates

• Study of this species can expand our knowledge about evolutionary history of species.
• It contains a chemical compound Didemnins which may be useful against viral diseases, Cancer.
  • Aplidine – is found effective for many types of cancer and trial are being conducted for ascertaining the efficacy against viral diseases like Covid-19.
  • Trabectedin- This is also effective against many types of cancer.
• Tunicates, especially Ascidiaceans, are used as food and a part of many delicacies around the world
• They can be a potential biofuel source. Researches are underway.

https://www.thehindu.com/sci-tech/science/science-for-all/article67067802.ece