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Wandering Albatross - How Do Sea Animals Drink Water? — Wandering Albatross

Yesterday we discussed how fish drink water. In the ocean, the problem isn’t water but salt. Ocean fish are designed with specialized gills that support the kidneys in getting rid of salt accumulations that would otherwise pickle the fish. Obviously, not all animals that live in the ocean have gills. How do sea animals drink water?

Albatrosses and petrels are birds that can spend a year or more in the open ocean, but they need to drink water. Whales and seals also do not have land-based water supplies, and yet, like all mammals, they need water to survive. So how do sea animals drink water when ocean water is salty? God’s design of living creatures always includes unusual equipment to enable them to deal with their environment.

In the case of sea birds, they have a set of salt glands in their heads that connect to the bird’s nostrils. The birds drink seawater, but the glands are so efficient that within three hours, all of the salt is removed through the nostrils.

Whales and other aquatic mammals produce urine that has extremely concentrated salt content. By allowing high salt concentrations in the urine to diffuse into the ocean, the salt never reaches toxic levels inside the animal. An interesting sidelight to this is that the milk of these sea mammals is very low in water content. In that way, they conserve water. Milk from seals has only half the water content of lean hamburger.

Everywhere we look in the natural world, we see that a wonder-working hand has gone before. These marvelous designs are not the product of mindless chance. They show an Intelligence who created with purpose and wisdom. When we realize that ocean water has high salt content, we question, “how do sea animals drink water?” God already took care of that.

In Job 38-40, God challenged Job to advance his understanding of God’s power and wisdom by considering the natural things of creation. When Job questioned God’s wisdom and purpose in his personal struggles, he did not recognize the wisdom shown in creation’s design. We too need to look at what God has done and “know there is a God through the things He has made” (Romans 1:18-20).

Data from National Wildlife magazine, June/July 1995, pages 30-34.

Have you ever wondered how a fish drinks water? Your first reaction is probably something like, “It opens its mouth.” Like most things in life, it isn’t that simple.

All living things necessarily have some saltwater content in their bodies to keep chemical balance allowing life to exist. The fluids inside an ocean-dwelling fish are only about a third as salty as the ocean itself. The water inside the fish’s body tends to leave by osmotic pressure, which is the tendency of fluids to move through membranes toward higher concentrations. To avoid this loss of water, the fish does simply open its mouth and drink seawater. But that brings large amounts of salt into the fish’s body. The salt concentration would be more than the fish’s kidneys could handle. To aid the kidneys, the gills of ocean fish are designed to expel salt, so the fish isn’t pickled by it.

In freshwater fish, the osmotic pressure is reversed, so the fluids inside the fish are saltier than the water outside. The skin of a freshwater fish is designed so that water seeps in through its skin and gills. Therefore, the fish doesn’t have to drink at all. When a salmon leaves the ocean and enters a freshwater stream, it merely stops drinking. Like freshwater fish, it depends on its skin to bring in its water needs.

Now that you know how a fish drinks water, the next question would be about other creatures that spend their time in the sea. Birds like albatrosses and petrels can spend more than a year at sea, and whales and seals live in the ocean 24/7/365. How can they avoid being poisoned by the salt? We’ll discuss that tomorrow.

God’s design of life includes fitting living things with specialized equipment to survive in every environment. Fish are remarkable creatures specially equipped for the waterworld in which they live.

Data from National Wildlife magazine June/July 1995, pages 30-34.

Tag: saltwater

How Do Sea Animals Drink Water?

How a Fish Drinks Water