(一)----阐明文 All (1)_______ things must fight to stay alive
They have to feed on something and at the same time avoid being (2)_______
Therefore they have to solve this big problem of staying alive in their own way
The danger of being eaten in the sea is great
Those plants and animals that do survive usually (3)_______ very fast and in great numbers
(4)_______ sea animals have defensive devices which help them to survive
The jelly fish have (5)_______ tentacles (触角) which are used for attack and defense
Another method of (6)_______ which sea plants and animals use is disguise
They usually have the same (7)_______ as their surroundings
In order to stay alive, animals need to have good senses
Fishes have sharp eyes
Almost all animals are sensitive to (8)_______
Fishes judge movemen