Fish can’t talk, but they do have gills—and that’s where our voices come from. Just like fish, human embryos have gill arches (bony loops in the embryo’s neck). But in humans, our genes steer them in a different direction. Those gill arches become the bones of your lower jaw, middle ear, and voice box.

Seven body organs you can live without

• Spleen. This organ sits on the left side of the abdomen, towards the back under the ribs.
• Stomach.
• Reproductive organs.
• Colon.
• Gallbladder.
• Appendix.
• Kidneys.

So one main reason humans can’t grow wings is because our genes only let us grow arms and legs.

Like fish, the remnants of an embryonic bony tail are buried in our lower backs-the coccyx or tailbone-stunted by a loss of molecular signals that would otherwise cause it to grow out like an arm or leg. Thus, humans and fish embryos share mechanisms for controlling tail form.”

Tails are used for balance, for locomotion and for swatting flies. We don’t swing through the trees anymore and, on the ground, our bodies are aligned with a centre of gravity that passes down our spines to our feet without needing a tail to counterbalance the weight of our head.

Humans do have a tail, but it’s for only a brief period during our embryonic development. It’s most pronounced at around day 31 to 35 of gestation and then it regresses into the four or five fused vertebrae becoming our coccyx. A tail would just get in the way and be a nuisance to this type of locomotion.”

The first is that human stomachs have difficulty digesting raw leaves and grasses. Animals such as cows, on the other hand, have a specialized stomach with four chambers to aid in the digestion of grass (a process called rumination).

Contrary to popular belief, human canines are not for tearing and ripping meat. Instead, our ancestors used them to fight male rivals for mating rights. Over time, human species evolved smaller and smaller canines as we stopped using our teeth as weapons. See more stories on Insider’s business page.

Most animals without backbones, known as invertebrates, have no tails. Among these are spiders, most insects and frogs. However, every species of mammal has a tail at some point in its development. Human embryos possess tails during their fifth to eighth week of development.

Taste sensations Other animals naturally have no tongues, such as sea stars, sea urchins and other echinoderms, as well as crustaceans, says Chris Mah via email. Mah is a marine invertebrate zoologist at the Smithsonian National Museum of Natural History and has discovered numerous species of sea stars.

There are no known limbless species of mammal or bird, although partial limb-loss and reduction has occurred in several groups, including whales and dolphins, sirenians, kiwis, and the extinct moa and elephant birds.

Symphylans have more than 200 species, with the young having 12 limbs while the adults grow up to 24. They lack eyes, and therefore, their sense organs come in the form of long antennae.

amelia: Medical term for the congenital absence or partial absence of one or more limbs at birth. Amelia can sometimes be caused by environmental or genetic factors. amputation: The cutting off of a limb or part of a limb. bilateral amputee: A person who is missing or has had amputated both arms or both legs.

Snakes don’t blink because they do not have eyelids. Each eye is covered with a single clear eye scale. These eye scales protect eyes from injury and prevent the eyes from drying out. That is the reason snakes are unable to blink their eyes and sleep with open eyes.

Snakes have no visible ear, so they don’t hear sounds as we do. They have vestiges of the apparatus for hearing inside their heads, and that setup is attached to their jaw bones, so they feel vibrations very well and may hear low-frequency airborne sounds.

For snakes, that answer can be complicated. Snakes don’t really hibernate in the winter in the sense most of us are familiar with. Instead, they go into a state called brumation. During brumation, snakes live in their dens, but they’ll come out to bask in the sun on pleasant winter days.

snakes definitely don’t like loud noises, and just like they can hurt your ears, they can probably hurt their (internal) ears.