Question

Which statement about compound eyes is true? a. They do not contain a lens or lenslike structure. b. They cannot sense color. c. They have one ommatidium per eye. d. They are found in insects and also many vertebrates. e. They probably have less resolving power than single-lens eyes.

Short answer

The correct answer is e. They probably have less resolving power than single-lens eyes.

Step-by-step solution

Understanding what a compound eye is

A compound eye is a type of eye found mainly in arthropods such as insects and crustaceans. It consists of an array of small visual units known as ommatidia. Each ommatidium functions as a separate photoreceptor unit.

Evaluating the first statement

The first statement is false. A compound eye has a lens structure; each ommatidium has its own lens.

Evaluating the second statement

The second statement is also false. Many insects can sense color, especially those active during the day.

Evaluating the third statement

The third statement is not accurate. Each compound eye contains numerous ommatidia.

Evaluating the fourth statement

This statement is false. Compound eyes are common in arthropods (insects, crustaceans) but are not found in vertebrates.

Evaluating the fifth statement

The fifth statement is true. Compound eyes don't have as high resolving power as single-lens eyes, which is why arthropods rely more heavily on motion than on form to recognize objects.

Key concepts

Ommatidium

One of the most fascinating aspects of biology is how creatures see the world. Insects and other arthropods have a unique visual system composed of multiple micro-lenses, each called an ommatidium. Imagine the ommatidium as a tiny camera, complete with its own lens, light-filtering capabilities, and photoreceptor cells. These minuscule units work together to capture a mosaic of images, providing a wide-angle view of the arthropod's surroundings.
While we humans have just one lens in each eye to create an image, arthropods may have thousands of these ommatidia comprising their compound eyes. This structure is not to be underestimated—it allows them to detect fast movements and stay alert to the teeming life around them. However, the trade-off is the clarity of the image; each ommatidium sees just a snippet of the scene, resulting in less detail than what's achieved with our single-lens eyes.

Arthropods' Vision

Delving deeper into the world of arthropods' vision, one discovers a rich tapestry of visual capability that ranges vastly across different species. Arthropods' vision includes not just insects, but also crustaceans like crabs and lobsters, each employing their compound eyes for survival. Some nip at the edges of color and light, capturing nuances of wavelengths and polarized light to communicate, mate, or forage.
Others are adapted to the dark, murky depths or the night's embrace, where even the slightest gleam can inform them of potential food or danger. It's a myth to think that these creatures are colorblind or wholly limited in their vision—indeed, many exhibit a remarkable sensitivity to various hues and brightness, an apt reminder of nature's ingenuity in tailoring senses to an organism's ecological niche.

Photoreceptor Units

Now, reflect on the individual photoreceptor units that constitute the ommatidium. These are comparable to the pixels on a digital screen—each one captures a distinct element of light, with pigments tuning in to specific wavelengths. The quantity and type of photoreceptor cells dictate the kind of light an arthropod can perceive, whether it's the ultraviolet spectrum favored by many pollinators or the green hues that dominate a mantis shrimp's vision.
These units tirelessly gather light, shading the arthropod's behavior and feeding choices with their interpretation of the world. While compound eyes might not fare well in capturing sharpness or depth as human eyes do, they excel in motion detection, which is paramount for survival in the bustling insect and crustacean worlds. The intricate, kaleidoscope-like view they offer is a product of evolution—perfectly tuned to these creatures' survival needs.