Convergent Evolution and Carcinization

Convergent Evolution and Carcinization - King Crab
King Crabs are not true crabs.

When unrelated species of animals or plants have common features, evolutionary biologists call it “convergent evolution.” There are many examples, such as:
* Dolphins and bats use echolocation to find food.
* Titan arum and rafflesia plants use putrid odor to attract pollinators.
* Nightingales and humpback whales sing similar songs just for beauty.

Those are only a few of the vast number of examples that scientists explain as convergent evolution. You can probably think of others. For example, bats, birds, and insects all have wings, but they are not related. In addition, unrelated venomous or poisonous creatures often wear bright colors as a warning, for example, snakes, frogs, and insects. Usually, the convergent features of various animals and plants serve an obvious purpose for the species’ survival.

Perhaps the most repeated convergence appears in the crab-like body shape. A crab has a flat, rounded shell and a tail that tucks under its body. Evolutionary biologists say that body plan has “evolved” at least five times. Scientists even have a name for this phenomenon. They call it “carcinization,” but they can only guess why it happened.

The result of carcinization is that many unrelated crustaceans resemble crabs. As a result, we often call them crabs even though they are not true crabs. A familiar example is the so-called king crab. Crab-shaped animals come in a wide range of sizes and live in various habitats, from the oceans to the mountains. So, with these creatures living in diverse ecosystems, scientists have difficulty explaining why they evolved the same body plan. Some suggestions include the tucked-under tail providing greater safety from predators or the body shape allowing them to move sideways.

We have a suggestion of why the crab shape, or carcinization, shows up in so many different crustaceans. Rather than convergent evolution, the common traits can be explained by a common Creator. That would explain why these creatures have the DNA building blocks for crabbiness – oops, I mean crab body shape.

— Roland Earnst © 2023

Extreme Plant Design – Rafflesia

 Extreme Plant Design - Rafflesia

The world’s largest and most awful-smelling flowers grow in the rain forests of the Philippines, Malaysia, Indonesia, and Thailand. They are produced by about 28 species of plants in the genus Rafflesia. These examples of extreme plant design have the odor and even the appearance of rotting flesh. 

Rafflesia are parasitic plants that grow under the bark of woody vines in the genus Tetrastigma. The vines of Tetrastigma are also parasitic plants that use host trees to reach sunlight for photosynthesis. So you could say that makes Rafflesia plants parasites of parasites. Rafflesia plants grow inside the Tetrastigma vines so that their only visible part is the flower. They have no roots or stems.

The Rafflesia flowers have five petals and can be 40 inches (100 cm) or more in diameter and weigh 22 pounds (10 kg) or more. Because of the odor of these flowers, they attract flies and insects that feed on dead animals. Those insects transfer pollen from the male flowers to the female flowers, which the males outnumber. 

But that isn’t the end of this extreme plant design story. Tetrastigma vines have a defense mechanism to prevent the Rafflesia from growing and taking energy from them. They produce chemicals called benzylisoquinoline alkaloids that are related to morphine and codeine. Those chemicals sometimes prevent the Rafflesia from growing in the Tetrastigma vine. However, it doesn’t work all the time. Jeanmaire Molina, a plant biologist at Long Island University, is trying to find out why. She thinks that Rafflesia may have a way to suppress the Tetrastigma’s alkaloid production. 

Scientific American magazine quoted Harvard biologist Charles Davis commenting that this research into extreme plant design is essential to understanding the interaction between parasites and hosts. He said that “plants are incredible chemists.” We agree that plants are incredible chemists, but only because the Master Chemist has fine-tuned plants and all of life to survive and thrive on this incredibly well-designed planet. God has given us plants to provide oxygen, food, and a wide range of medical products that enrich our lives. 

In a previous post (December 4, 2021), we reported on the titan arum (Amorphophallus titanum), which is known as the “corpse flower.” It also produces the smell of a rotting corpse and attracts flies for pollination. Interestingly, the titan arum uses the same means for pollination, but it is not related to Rafflesia. Evolutionists would call that “convergent evolution,” but we call it evidence of a common Designer. 

— John N. Clayton © 2022

Reference: Scientific American, March 2022 page 22, and Wikipedia