IAS Gyan

Daily News Analysis


15th July, 2023 Environment

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  • 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.


  • 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.


Consider the following statements about Tunicates:

1. These are considered significant to understand the evolutionary history.

2. This species could be useful against various types of cancer.

Which of the statements given above is/are correct?

A. 1 only

B. 2 only

C. Both 1 and 2

D. Neither 1 nor 2

Answer: (C)