TAILIEUCHUNG - BIOMES OF THE EARTH - OCEANS Phần 6

Tham khảo tài liệu 'biomes of the earth - oceans phần 6', ngoại ngữ, anh ngữ phổ thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 120 OCEANS school reflect this wave back. This array of vibrations provides the fish with a highly detailed picture of its surroundings and the movement of objects nearby. The great advantage of schooling is probably to reduce predation. It is more difficult for a predator to find a single school rather than hundreds of widely scattered individuals. When a predator attacks a school the fish scatter making it difficult for the hunter to single out one individual. Living in a school each fish has slightly improved chances of survival. Bony fishes reproduce in a wide variety of ways. Unlike cartilaginous fishes which lay few eggs or bear live young many bony fishes release thousands of eggs at a single spawning. The male then fertilizes the eggs in the water. A female North Atlantic cod typically produces about 10 million eggs a year. The eggs of cod and other oceanic species float up to the surface waters and form part of the plankton community. Zooplankton and fish eat the eggs and fish larvae so from the original millions few survive to maturity. Those species that live in coastal waters on the seabed or among floating seaweed tend to produce fewer eggs and spend more time and energy in their care. Several species of coral-reef cardinal fish are mouth-breeders. Males keep the fertilized eggs in the mouth to protect them until they hatch. In seahorses the pregnant female places her eggs in a brood pouch on her partner s belly. The male incubates the eggs and when they hatch tiny seahorses wriggle out of his pouch opening he gives birth. Marine reptiles Of about 8 000 living species of reptiles only about 80 live in seawater or brackish water diluted seawater . Marine reptiles include sea snakes sea turtles two species of crocodile and a lizard. Around 400 million years ago complex forms of life began to invade the land. Within the space of 80 million years water-living algae gave rise to land-living mosses and ferns and some marine arthropods joint-limbed .

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