Irreducible complexity is not a feature that we only see at the biochemical level or in complicated organs. Many biological systems possessed by living things are irreducibly complex, and invalidate the theory of evolution for that reason. The extraordinary reproductive method of Rheobatrachus silus, a species of frog living in Australia, is an example of this.

The females of this species use a fascinating method to protect their eggs after fertilization. They swallow them. The tadpoles remain and grow in the stomach for the first six weeks after they hatch. How is it possible that they can remain in their mothers' stomach that long without being digested?

A flawless system has been created to enable them to do so. First, the female gives up eating and drinking for those six weeks, which means the stomach is reserved solely for the tadpoles. However, another danger is the regular release of hydrochloric acid and pepsin in the stomach. These chemicals would normally quickly kill the offspring. However, this is prevented by a very special measure. The fluids in the stomach of the mother are neutralized by the hormonelike substance prostaglandin E2, which is secreted first by the egg capsules and then by the tadpoles. Hence, the offspring grow healthily, even though they are swimming in a pool of acid.

The females of this species hide their young in their stomachs throughout the incubation period, and then give birth to them through their mouths. But in order for this to happen, a number of adjustments have to be made, all at the same time and with no mistakes allowed: The egg-structure has to be set up, the stomach acid must be neutralized, and the mothers have to be able to live for weeks without feeding.

How do the tadpoles feed inside the empty stomach? The solution to this has been thought of, too. The eggs of this species are significantly larger than those of others, as they contain a yolk very rich in proteins, sufficient to feed the tadpoles for six weeks. The time of birth is designed perfectly, as well. The oesophagus of the female frog dilates during birth, just like the vagina of mammals during delivery. Once the young have emerged, the oesophagus and the stomach both return to normal, and the female starts feeding again.363

The miraculous reproduction system of Rheobatrachus silus explicitly invalidates the theory of evolution, since the whole system is irreducibly complex. Every step has to take place fully in order for the frogs to survive. The mother has to swallow the eggs, and has to stop feeding completely for six weeks. The eggs have to release a hormonelike substance to neutralize stomach acids. The addition of the extra protein-rich yolk to the egg is another necessity. The widening of the female's oesophagus cannot be coincidental. If all these things failed to happen in the requisite sequence, the froglets would not survive, and the species would face extinction.

Therefore, this system cannot have developed step-by-step, as asserted by the theory of evolution. The species has existed with this entire system intact since its first member came into existence. Another way of putting it is, they were created.

363 William E. Duruelleman & Linda Trueb, "The Gastric Brooding Frog," Megraw-Hill Book com., 1986.