Homologous structures Definition

Homologous structures space organs or skeletal aspects of animals and organisms that, by virtue of your similarity, imply their connection to a usual ancestor. This structures carry out not need to look specifically the same, or have actually the very same function. The most important part, together hinted by your name, is that they space structurally similar.

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Examples that Homologous Structures

A tale of Tails

Monkeys, cats, rats and also other mammals have actually tails. In mammals, the tail is an expansion of the torso, make of functional vertebrae. Tails primarily role to ward off insects, but they can additionally serve as sources of balance for an ext aloof species, choose cats.

Humans possess a comparable feature recognized as the coxxyx, or tailbone. Likewise an extension of the torso, that is make of what some scientists contact “rudimentary vertebrae” and is believed to have actually once been a fully-formed tail. Unlike other mammal tails, however, it at this time serves no purpose.

The fact that the structure of the human coccyx so carefully resembles that of an animal tail offers scientists reason to attach it come a typical ancestor between mammals and humans. Due to this link, the mammalian tail and the human being coccyx room homologous structures.

Eye have a irradiate Bulb

Not all animals can check out the method humans do. Deep sea creatures, like the chimera, live in an setting so dark, their eyes have not emerged the advanced discriminatory skills that have, person eyes. Their visual cues come from irradiate receptors near the front of your skull, and they carry out not see color or depth.

Like light receptors, the person eye captures light and also sends that info to the brain. As we human beings have progressed in an environment completely illuminated by the sun, their eyes save on computer extra filters, or photoreceptors, that allow us to perceive colors, shadow, and also distance. More specifically, rod-shaped photoreceptors allow us to watch black-and-white and also shadow, and cone-shaped photoreceptors allow us to check out color and saturation.

The photo shows a blind chimera that “sees” v light receptors.

The photo shows a human eye supplies rods and also cones to transform light right into images.

Thanks come evolution and environment, the function of the human eye emerged into something far much more sophisticated than that of deep-sea creatures, like the chimera. However, despite our capacity to see full images and also the chimera being minimal to only shadow, the reality that both eyes and also light receptor “see” by absorbing light confirms there feasible connection come a typical ancestor and, therefore, structurally homologous.

Raise her Head High

Giraffes are the subject of wonder and also amazement, and also rightly so. Because Carl Linnaeus first classified them in 1758, these pets have captured the eye of every who check out the Sahara.

Their lengthy necks, especially, gather the mass of attention. Although they measure approximately eight feet in length and also weigh end 600 pounds, they contain only seven cervical vertebrae, or neck bones. Looking at the image below, we see that these bones have tendency to be longer – around one foot in length.

Humans additionally have cervical vertebrae, however they have tendency to be far shorter than those of the giraffe. Evaluating the person neck diagram, human being cervical vertebrae appear much much shorter and squatter than those that the giraffe.

A giraffe’s lengthy neck

Nonetheless, both human and giraffe necks contain seven bones. This number, when linked with the similar structure that the human and giraffe spine, allows the scientific neighborhood to posit the humans and giraffes, as different as they might be, re-superstructure a typical ancestor. Together such, your cervical vertebrae are structurally homologous.

Related biology Terms

Coccyx – The “tail bone” at the finish of a mammal’s spinal column. The coccyx may be written of fused vertebrae, or that may extend into a tail. Cervical vertebrae – The bones that provide support because that the upper spine.


1. Homologous structures do not need to have the very same function. Instead, lock must: A. link both species to a typical ancestor. B. Look specifically the same. C. move in the very same direction. D.

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Follow similar growth patterns.

Answer to inquiry #1
A is correct. Homologous structures have to be comparable enough that they imply that two varieties share a common ancestor. However, they do not need to serve the exact same function.