Background Facts on Saltwater Fish in the Ocean
There are many different species of ocean-dwelling fish in the world. Marine fish come in many different shapes and sizes and are found at depths ranging from just below the ocean's surface to several miles deep. Not all ocean-dwelling fish live in salt water throughout their life. Some marine fish migrate to freshwater environments.
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Numbers
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There are approximately 20,000 different species of fish in the ocean. The most common of these are members of the Cyclophone family. Cyclophones are found in deep water in many parts of the world with the exception of the South and North poles. They are often called "bristle mouth" fish.
Migration
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Fish that are born in freshwater environments but spend most of their lives in saltwater are referred to as "anadromous." Anadromous fish, such as salmon, sturgeon, striped bass, shad and smelt, live in the ocean but migrate to freshwater rivers and streams during spawning season. Fish that are born in the sea and spend the majority of their life in freshwater streams and rivers are called "catadromous." Catadromous fish, such as many species of eel, migrate to the ocean during spawning season.
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Size
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The largest ocean-dwelling fish species is the whale shark. The whale shark can weigh several tons and measure up to 50 feet long. Another large species of fish is the basking shark, which can measure up to 40 feet in length. The smallest ocean-dwelling species of fish is the male deep-sea anglerfish, which measures only about 6 mm in length. The male anglerfish attaches itself to the female of the same species and gets all of its nutrients from her body.
Reproduction
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The females of many species of ocean-dwelling fish lay eggs that are then fertilized by the male. Some species of saltwater fish, however, give birth to live babies instead. These species of fish are known as "viviparous" fish. Many species of shark are viviparous, as well as Pacific perch.
Depths
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Different species of fish are found at different depths in the ocean. Many live at shallow depths near the coastline and can be seen easily by humans, while other kinds of fish can live as much as seven miles below the surface of the water. These fish are known as deep-sea fish. Because it can be so dark at the bottom of the ocean, some deep-sea fish such as viperfish utilize light-producing bacteria to attract prey in the dark.
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References
Resources
- Photo Credit ocean image by G.g1 from Fotolia.com
