Animals - Fish

3 groups:

• jawless: no biting jaws, but sucker disks with a rasping tongue and small teeth made of keratin. The lampreys (七鳃鳗) are the only jawless fish.
• cartilaginous: skeleton made of cartilage instead of hard bone. Most are predators with sharp senses. Sharks and rays: most fish are bony, but sharks and rays have skeleton made of springy cartilage.
• bony: have a hard bony skeleton and a swim bladder.

Fins

• lobe fin: fleshy fins, used to "walk" on the seabed or riverbed
• ray fin: most fish belong to this group. fins are supported by a fan of jointed rods called rays.

Species

• Sturgeon 鲟. Caviar is made from the eggs of the sturgeon.
• mudskipper: can survive out of water by absorbing oxygen from the air through its skin.

鲨鱼

鲨鱼是鱼，不是哺乳动物。鲨鱼用鳃呼吸，鲸鱼用鼻子呼吸，鲨鱼是冷血动物，鲸鱼是温血动物，鲨鱼全身有盾鳞，鲸鱼皮肤光滑没有鳞片。

Basking shark: the world's second largest fish, after the whale shark. Feed by swimming with its vast mouth gaping wide.

Ray

• Giant Manta ray: the biggest ray. Can leap out of the water when trying to avoid large predators.
• Batoidea 鳐总目,又名魔鬼鱼；Rajiformes 鳐形目；Ray 鲼；Stingray 魟； 鲼形目=燕魟目; Mobula 蝠鲼
• Manta ray has the largest brain of fish