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The statocyst is a balance sensory receptor independently found in different organisms like: some aquatic invertebrates, including bivalves, [206] cnidarians, [207] echinoderms, [208] cephalopods, [209] and crustaceans. [210] Also found in single-cell ciliate. A similar structure is also found in Xenoturbella. [211]
Functionally similar features that have arisen through convergent evolution are analogous, whereas homologous structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions.
They may or may not perform the same function. An example is the forelimb structure shared by cats and whales. Analogous structures - structures similar in different organisms because, in convergent evolution, they evolved in a similar environment, rather than were inherited from a recent common ancestor. They usually serve the same or similar ...
Human vestigial structures also include leftover embryological remnants that once served a function during development, such as the belly button, and analogous structures between biological sexes. For example, men are also born with two nipples, which are not known to serve a function compared to women. [47]
The three small bones in the middle ear of mammals including humans, the malleus, incus, and stapes, are today used to transmit sound from the eardrum to the inner ear. The malleus and incus develop in the embryo from structures that form jaw bones (the quadrate and the articular) in lizards, and in fossils of lizard-like ancestors of mammals.
Homologous structures in the external genitalia. This list of related male and female reproductive organs shows how the male and female reproductive organs and the development of the reproductive system are related, sharing a common developmental path. This makes them biological homologues. These organs differentiate into the respective sex ...
Evidence for the evolution of Homo sapiens from a common ancestor with chimpanzees is found in the number of chromosomes in humans as compared to all other members of Hominidae. All hominidae have 24 pairs of chromosomes, except humans, who have only 23 pairs. Human chromosome 2 is a result of an end-to-end fusion of two ancestral chromosomes ...
Using Darwin's theory evolutionary embryologists have since been able to distinguish between homologous and analogous structures between varying species. Homologous structures are those that the similarities between them are derived from a common ancestor, such as the human arm and bat wings.