Why in News?
Actinarctus odissi is a newly discovered species of marine tardigrade—microscopic, structurally resilient animals colloquially known as "water bears" or "moss-piglets."
Discovery & Habitat
- Location: It was extracted from sandy ocean sediments at a depth of 14 metres in the shallow marine waters of the Bay of Bengal, specifically near Markandi in Odisha, India.
- Method of Extraction: Scientists used a specialized mechanical scoop called a Van Veen grab from a local fishing trawler to collect the bottom sediment and then carefully isolated the microscopic creatures using microscopes and ultra-fine brushes.
- Understudied Realm: While there are over 1,500 known species of tardigrades worldwide, marine tardigrades are highly understudied and account for only about 17% of total tardigrade diversity.
Anatomical Features of Actinarctus odissi
- Body Shape: It possesses a unique dome-shaped body surrounded by transparent, wing-like lateral flaps called alae, which are held up by translucent internal pillars.
- Shorter Wings: Unlike its sister species within the genus that feature long wings, Actinarctus odissi has noticeably shorter lateral wings.
- Unique Sculpturing: The back (dorsal side) of this micro-animal is heavily sculptured with unique, tiny trombone-shaped pillars.
- Sensory Appendages: It features simple, un-split sensory organs on its back legs that are significantly shorter than those of its cousins, along with blunt-tipped (rather than sharp) sensory appendages.
General Tardigrade Characteristics
- Nickname: Tardigrades are microscopic, multicellular animals popularly referred to as "water bears" or "moss-piglets".
- Physical Structure: They are typically short (0.05 mm to 1.2 mm in length), plump, segmented, and bilaterally symmetrical with four pairs of legs ending in claws.
- Diet: They rely on feeding on the fluids of animal cells, plant cells, and bacteria.
- Extreme Resiliency: They are world-renowned for surviving extreme environmental hazards, including freezing cold, boiling heat, high radiation, and even the vacuum of outer space.
- The "Tun" State: Under unfavourable conditions, they enter a state of suspended animation called cryptobiosis (or the "tun" state). Their bodies dry out into a ball, and their metabolism drops to a staggering 0.01% of normal levels, allowing them to wait out hostile conditions for decades.
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