The highly intelligent small toothed cetacean recognized by their curved mouths that give them their permanent smile are the very social dolphins, known for their playful behaviour live in groups called school or a pod and can use echolocation for finding the exact location of objects especially for finding their food that includes other small fishes, squids and crustaceans.
There are nearly 38 species of dolphins that reside in the oceans and the other 3 remaining species out of the 5 are residing in the freshwater streams and rivers. As they inhabit near to the coastlines they are susceptible to several anthropogenic problems like habitat degradation, overfishing, plastic pollution, chemical discharge, entanglements in ghost nets, death due to accidental catch in fishing gear, re-occurring accidents with motorboats and big vessels, dredging activities to name a few, as a result, they are facing several threats like the extinction of the Yangtze River dolphins or show a decline in their population.
In India, Ganges river dolphin is one of the five river dolphins found in the world. The species is distributed in Ganges and Brahmaputra river basins of India, Nepal and Bangladesh and are protected under Schedule I of Wildlife Protection Act (1972).
Thus, 14 April globally is observed as the “World Dolphin Day” that celebrates the notable uniqueness of this marine mammal to educate people about their importance and the need to conserve them and their habitat.
Microbial Dose:
As we know microbes are ubiquitous, researchers have found two new unknown bacterial lineages in the mouth of dolphins and Dr David Relman's lab has studied one of them and named it in honour of the dolphins as Delphibacteria. By identifying and reconstructing the bacterial lineages by their genomes from the short chunks of bacterial DNA it is predicted that this microbe expresses a property called denitrification that affects the dolphin's oral health causing inflammation and a painful gum disease. Denitrification also occurs in plaque on human teeth.
References:
Background and approach. Wildlife Institute of India, an Autonomous Institute of MoEF, Govt. of India. https://wii.gov.in/campa_dolphin
Gajdoczki N. 10 Fascinating Dolphin Facts [Internet]. 2013 [cited 2020 Apr 14]. Available from: https://blog.padi.com/2013/09/04/10-fascinating-dolphin-facts/
Lanese N. Dolphin mouths house “dark matter of the biological world” [Internet]. News Center. http://med.stanford.edu/news/all-news/2017/11/dolphin-mouths-house-dark-matter-of-the-biological-world.html
