Size and Internal Anatomy

A previous post focused on wings, which are a very important part of every bird. Wings, however, are not the only aspect of bird anatomy mentioned in the Bible. In regard to bird design, the Bible refers to overall size, as well as both internal and external components of anatomy.

When it comes to size, birds, on average, are smaller than other creatures. When God was confirming a covenant with Abram, He had Abram bring a heifer, a goat, a ram, a turtledove, and a young pigeon. In preparing the animals, Abraham divided the larger animals but not the smaller birds. “Then he brought all these to Him and cut them in two, and laid each half opposite the other; but he did not cut the birds” (Genesis 15:10). God later gives the instruction not to “sever” birds given in sacrifice (Leviticus 1:17).

The New Testament also refers to the small size of birds. The sparrows were so small and insignificant that they had little value. “Are not two sparrows sold for a cent?” (Matthew 10:29). “Are not five sparrows sold for two cents?” (Luke 12:6).

On the other hand, there are also large birds, and the Bible recognizes this fact. “But the two wings of the great eagle were given to the woman” (Revelation 12:14). Ezekiel 17:3 and 7 also mention a “great eagle.”

The Bible mentions several aspects of internal anatomy. One of these is a bird’s flesh. “All flesh is not the same flesh, but there is one flesh of men, and another flesh of beasts, and another flesh of birds, and another of fish” (1 Corinthians 15:39). Birds have flesh that is different from the flesh of other living things. Flesh is the soft substance of the body that surrounds the skeleton (muscle and fat). Anyone with a diverse appetite is aware of this difference. There are great differences between a fish fillet, a T-bone steak, and a chicken breast. Birds’ distinct flesh quality is affected by things like the protein-to-fat ratio, their metabolic rate, their breathing system, their reproductive processes, and the tendency for fat to be found in pockets rather than marbleized within the muscles.

The Bible acknowledges that birds have blood. “You are not to eat any blood, either of bird or animal, in any of your dwellings” (Leviticus 7:26). In instructions for a sacrifice involving birds, God says, “Its blood is to be drained out” (Leviticus 1:15). Drops from an injured bird will be bright red. The blood of birds has the same basic components as human blood (red blood cells, white blood cells, platelets, plasma), but bird blood is especially designed to meet their high metabolic rate, their oxygen demand in flight, and their frequent physical activity. For example, their red blood cells have a nucleus; this difference from mammals enhances their circulatory system and helps them maintain energy during flight.

The Bible records that birds also breathe air. “All flesh that moved on the earth perished, birds and cattle and beasts and every swarming thing that swarms upon the earth, and all mankind; of all that was on the dry land, all in whose nostrils was the breath of the spirit of life, died” (Genesis 7:21-22). Do birds have nostrils? Yes. They aren’t exactly like human or mammal nostrils, but their beaks have openings for the intake of air. Birds have a complex respiratory system that takes up about one-fifth of their interior. Numerous air sacs are connected to the lungs, and the air that the birds breathe in passes in a cycle, starting with the posterior air sacs, then moving to the lungs, then to the anterior air sacs, and then is exhaled. The lungs purify the air, and the air sacs act like pumps to force the air through the process.

How about this internal detail? “He shall also take away its crop” (Leviticus 1:16). The crop is an interesting feature of birds. In essence, it is a food storage pouch located between the esophagus and the stomach. The crop helps to manage a bird’s caloric needs and also begins to prepare the food for digestion. Birds have to eat when they get the opportunity, and sometimes that means they have to eat a lot of food all at once. The crop stores what their body doesn’t need immediately and gradually releases it throughout the day. Many birds feed primarily in the morning and become less active in the heat of the day, which explains why early morning is a birder’s favorite and most rewarding time.

Of course, God knows all about the internal workings of birds, because He designed and created them, giving them the unique features suited for the way He expected them to live and function. Next time we’ll look at external anatomy.

Scripture taken from the NEW AMERICAN STANDARD BIBLE ®, Copyright © 1960, 1962, 1963, 1968, 1971, 1972, 1973, 1975, 1977, 1995 by The Lockman Foundation. Used by permission.