The Fascinating Reason Why These Animals Shed

Key Points:

• Some animals on this list shed their fur or feathers rather than their skin, such as dogs, sheep, and birds.
• This list includes crabs, snakes, and people!
• An unusual creature on this list is a species of frog that sheds its skin.

Many animals shed their outer layer. Molting is a way of ensuring the body grows and sets the creature up for the next stage of life. Many animals, such as the Dungeness crab, have rigid shells that do not grow as their bodies do. To allow for natural growth, these animals have an outer layer that breaks or molts and falls off.

Humans have bones and skin that grow with us, although we do shed our outer layer of skin (dead cells) throughout our lives. Animals that molt often do so in a dramatic way and multiple times as they transition to adulthood. Many organisms such as spiders, insects, birds, snakes, and crustaceans molt.

The molting process is unique for each of these animals that shed.

1. Crabs

The ability for growth isn’t the only reason crabs molt. When shedding its shells, the crab relieves itself of barnacles and parasites potentially living in its shell. Generally, a crab molts dozens of times throughout its life cycle. Crabs can even regenerate their legs.

When it’s time to molt, the crab forms a paper-thin shell under the existing one, absorbing nutrients for hardening its upcoming exoskeleton. Sucking in water, the crab expands its body and splits the old shell open. The crab begins a process that can take up to three hours, during which it wiggles out of the broken shell. The softshell eventually hardens.

2. Grasshoppers

The grasshopper lives for about a year. It goes from egg to nymph to adult. During that period, it molts five to six times during the nymph phase. Unlike a variety of arthropods that molt for their entire lives, the grasshopper reaches adulthood and stops the shedding process. The grasshopper has hormones that signal it needs to shed its underdeveloped exoskeleton to accommodate its increasing mass. The insect grows a new exoskeleton underneath the old one. It’s time to molt. The grasshopper sucks in air, increasing its frame and breaking the old shell. During the process, they’re easy prey and work quickly to finish the stage.

3. Snakes

One of the most common animals to shed skin, snakes molt and leave their old skin in one piece. But unlike other arthropods, snakes do not have exoskeletons. How often a snake will shed depends on the temperature, the amount of food, and other environmental factors. On average, terrestrial snakes shed their skin up to three times a year. It takes an average of two weeks for a complete molt. During this period, snakes get aggressive. This is because snakes shed their eye caps—special scales that cover and protect their eyes. Without these, snakes have impaired vision and feel vulnerable.

4. Bighorn Sheep

There are mammals that molt as snakes and insects do. A lot of these animals shed their wool, hair, or fur on a periodic or seasonal schedule. The largest wild sheep in North America, the bighorn, sheds its winter coat in the late spring and early summer. The molting minimizes heat stress in the hottest parts of the year. The shedding also makes navigation easier at higher, rugged elevations. Bighorn sheep shed their coats naturally. Some domestic breeds do not molt, so their wool grows continuously, often adding between 5 and 15 pounds each year, depending on the breed. That’s why farmers shear these animals a couple of times a year.

5. Frogs

Frogs shed their old skin to maintain healthy, functional skin, which is important for absorbing oxygen through their skin, especially when in water. Frogs breathe through their skin when in water. The process is relatively easy. When it’s time, the animal assumes a crouching, scrunched position that creates a rip in the old skin. The frog then stretches, and the old skin splits. The frog then peels the skin off. Once the skin is off, the frog eats the shredded skin. They do so to recover the nutrients lost by shedding in the first place. The skin contains calcium and other nutrients. If you are nearby with a camera, post-shedding is a great time to take a picture, as the frog’s patterns and colors are especially vibrant after the process.

6. Humans

The outermost layer of skin on humans, the epidermis, constantly evolves. When the skin is too dry, desmosomes and enzymes degrade and malfunction, causing cells to clump together. These clumps shed as visible scales or flakes, rather than as individual, invisible cells. Unlike most mammals, humans shed skin so gradually that it’s not even noticeable. But the fact is, according to Environmental Science & Technology, humans shed about 1.5 to 9 pounds of skin per year, according to various estimates. The number appears small, but over a lifetime, that’s approximately half your body weight. A lot of the dead cells fall off and become dust in the air. Quite a bit comes off when we scratch or wash.

7. Spiders

Like many creatures, spiders shed their exoskeletons to prevent growth stunting. The arachnid’s frame grows while its outer shell doesn’t. The spider has an outer shell consisting of an elastic inner layer and a rigid outer layer. When it’s time to shed, the spider releases unique hormones that encourage molting. As molting progresses, the inner layer breaks down. The spider absorbs the layer’s nutrients for later nourishment. When the new exoskeleton is about ready, the spider takes in air. The pressure enlarges its body and destroys the old exoskeleton. The spider pushes itself out and takes in more air to expand its new soft exoskeleton. The new shell hardens, completing the process.

8. Dogs

Shedding is critical to the animal’s fur and skin health. Many dog lovers live with the molting of their dogs. Most canines shed in the spring and autumn, depending on the environment, breed, and climate. Another factor is whether the dog has a single or double layer of fur. A shedding dog requires special maintenance, especially if you want to avoid hair in the air and on surfaces. Prevention includes regular brushing, using a shedding tool to remove dead hair before it falls off, keeping the dog hydrated, bathing with a de-shedding shampoo, and providing a healthy diet.

9. Birds

Keratin is a substance located in hooves, horns, fingernails, claws, turtle shells, and porcupine quills. The outer layer of the skin is the epidermis. This same surface is composed of dead cells made of keratin. There is also keratin in feathers. The compound is critical for flying creatures to stay in the air. Birds molt and replace worn feathers to have healthy wings for flying. Some species, like the songbird, also shed to keep their color beautiful for mating. But that brilliance is also a threat, as it makes you vulnerable to predators. Creatures with bright colors typically molt twice a year. It’s dull in the fall and bright in the spring. Birds that do not have a color change molt perhaps once a year.

10. Caterpillars

Caterpillars shed their exoskeletons four to five times during their growth stages. The insect outgrows its exoskeleton, expands its body, splits the outer layer, and crawls out. The exoskeleton is not like typical skin; it is more like a fingernail, sliding off as the old skin peels back from the front.

The shed process is important as the caterpillar increases its body mass up to 1,000 times. We refer to the stage between molts as an instar. During these periods, the caterpillar consumes tremendous amounts of food. Some caterpillar species can consume thousands of times their body weight during their larval stage, with most of this feeding occurring between molts. Additionally, caterpillars have six eyes, called ocelli or stemmata. They do not have lungs, and their insides (guts) move on their own. Caterpillars may eat a tremendous amount of food in their lifetimes; however, they do not have teeth.