Question

Describe the sequence of events that lead to aquatic mammals. Please include some adaptations needed for marine environments.

Answer 1

The aquatic mammals are group of mammals which completely or partially dwell in ocean. The first proto mammal that is known to have developed aquatic features is Castorocauda. In 1980s it was found that many fossils which are land based mammals shared structural similarity with the cetaceans and some of the skeletal features were same. The first reason why the transition might have occurred in the first place is for the lookout for untapped resources and food that reduced in the land. Another strong reason in the series of events of the changes in the evolution of the cetaceans to exploit the new resources that formed due to the plate tectonics or other environmental changes that took place nearly 50 to 55 years ago. Gradually with time, they were able to adapt to the niches in the aquatic body through its ability to swim. The second type of adaptation during the transition is the shift of the nostrils from front of the face to the head top.

The aquatic mammals do not majorly breathe underwater and the valvular nostrils and intranarial larynx exclude water while breathing and swallowing. They have developed strong sensory organs in order to navigate and move through water. They have also well adapted locomotion style that makes them fast swimmers. Different mammals have adapted in a different manner. Some mammals have four limbs that help to swim as well as walk. Some mammals like beavers, otters etc. have long, oily and waterproof fur which helps in trapping air to provide insulation.