| terrestrial | living on the land or on the ground, rather than in water, in trees or in the air |
| mammal | any animal that gives birth to live babies, not eggs, and feeds its young on milk. Cows, humans and whales are all mammals . |
| absent | not attending a place or event, especially when expected to |
| cetacean | connected with the group of creatures that includes whales and dolphins |
| baleen | a horny substance that grows as fringed plates from the upper jaws of some whales, acting to strain food, especially small crustaceans, from the water |
| speculate | to consider or discuss why something has happened or what might happen |
| blowhole | a hole in the top of the head of an ocean animal such as a whale or dolphin, through which it breathes |
| evolve | to develop gradually, especially from a simple to a more complicated form; to develop sth in this way |
| migrate | 1. to move from one part of the world to another according to the season
2. to go to another place or country in order to work |
| sacrifice | 1. the act of giving up something important or valuable so that you or other people can do or have something else
2. the act of killing a person or animal as part of a ceremony to honor a god or spirit; a person or animal killed to honor a god or spirit |
| rudimentary | basic, and not detailed or developed |
| captive | kept as a prisoner or in a confined space; unable to escape |
| responsiveness | sensitivity |
| rub | the action of rubbing part of the body; the action of rubbing something with a cloth, etc. |
| calf | a young animal of some other type such as a young elephant or whale
a young cow |
| quarter | a district or part of a town
one of four equal parts of sth |
| moderately | to an average extent; fairly but not very |
| stereoscopic | able to see objects with length, width and depth, as humans do |
| keen | quick to understand |
