Quick Answer
Narwhals do not have hair or fur covering their bodies like land mammals. Instead, they have a smooth, rubbery skin. However, narwhals are mammals like cows, dogs, and people, so they are born with some hair, but they shed it before or shortly after birth. Newborn narwhals have a soft, short, woolly coating over their bodies that starts falling out after a few days or weeks.
Narwhals Are Mammals That Lack Fur
Narwhals are medium-sized whales that live year-round in the Arctic waters around Greenland, Canada, and Russia. They are one of the 80-90 species of cetaceans, a group that includes whales, dolphins, and porpoises. Narwhals belong to the taxonomic order Cetacea which is divided into two suborders:
- Mysticeti – baleen whales like humpback and blue whales that filter feed on krill and small fish
- Odontoceti – toothed whales like orcas, sperm whales, belugas, and narwhals that hunt larger prey
As members of the order Cetacea, narwhals are marine mammals. Marine mammals share several key features that allow them to live their whole lives at sea:
- Streamlined torpedo-shaped bodies to move efficiently through water
- Flippers for steering and balance
- A thick layer of blubber for insulation in cold waters
- Nostrils on top of their heads that can close to prevent water from entering when submerged
- The ability to hold their breath underwater for long periods
Unlike fish, cetaceans are warm-blooded air-breathers that give birth to live young and nurse them with milk, just like land mammals. This makes narwhals and other cetaceans mammals, despite their fish-like appearances and adaptations for an aquatic environment.
All mammals share three distinguishing features:
- They have hair or fur at some point during their lives
- They produce milk to nurse their young
- They are warm-blooded (endothermic) so they can maintain a high constant internal body temperature
As mammals, narwhals possess hair follicles and produce hair as embryos. However, unlike fur seals, sea otters, and polar bears, narwhals do not retain a furry insulating coat in adulthood. Instead, they rely on their thick blubber layer for warmth and protection.
Narwhal Fur is Shed Before or at Birth
In the womb, a developing narwhal embryo will grow a coat of short woolly hair called lanugo. Lanugo likely helps keep the fetus warm. Around the second trimester, the lanugo is shed and replaced by a longer, more dense fetal fur.
At birth, a narwhal calf emerges coated in soft, short, grayish hair about 1 inch long. It may appear woolly or velvety. This fetal fur continues to be shed gradually over the narwhal’s first few weeks to months of life. As juvenile narwhals mature, they lose the last vestiges of hair, becoming completely hairless except for sparse hairs around the blowhole.
The purpose of narwhal fetal fur is uncertain. Since narwhal calves are born underwater, lanugo and fetal fur do not seem necessary for insulation right away. One theory is that the fur helps streamline the fetus or protect its skin during gestation. The hair may also provide sensory input about the environment or stimulation for the developing skin.
In some marine mammals like whales and porpoises, the fetal fur is shed before birth. In others like belugas and narwhals, it is retained for a short while after birth. Dolphins tend to keep some hair into adulthood around their blowholes. Every whale species has a slightly different hair growth and shedding pattern.
Comparison of Hair in Mammals
| Animal | Hair/Fur? | Type and Description | Purpose |
|---|---|---|---|
| Narwhal | Shed before or at birth | Short grayish coat about 1 inch long | May provide insulation, sensory input, or protection in womb |
| Beluga | Shed within first few months after birth | 1-3 inches long, slightly longer than narwhal fur | Likely same as narwhal fur |
| Dolphin | Some hair around blowhole | Few sparse hairs as adults | Purpose unknown |
| Sea otter | Yes, thick brown fur | Densest fur of any mammal | Insulates in cold Pacific ocean |
| Polar bear | Yes, shaggy clear fur | Long oily guard hairs over dense underfur | Provides insulation and water resistance |
| Dog | Yes | Varies by breed | Insulation, sensory input |
| Human | Yes, hair on head, face, body | Straight, curly, fine, coarse | Warmth, protection, visual signals |
This table compares how hair and fur differ among various mammals. Most land mammals and marine mammals like seals and sea otters retain thick fur for insulation. Aquatic mammals like whales, dolphins and narwhals that rely on blubber to stay warm tend to shed fetal fur before or soon after birth.
Why Narwhals Lack Fur
There are several theories as to why narwhals shed their fetal fur and do not retain fur into adulthood like their land-dwelling mammalian relatives:
- Streamlining – Body hair creates drag in the water. Hairless skin allows cetaceans like narwhals to swim quickly and efficiently.
- Thermoregulation – Narwhals depend on their thick blubber, countercurrent heat exchange in blood vessels, and aquatic environment to stay warm. Fur would be redundant.
- Reduced sensitivity – Hair contains sensory nerves. Removing hair may make narwhals less sensitive to cold temperatures.
- Hygiene – Smooth skin prevents algae, barnacles, and other marine growth from attaching to the body.
- Maneuverability – Hair limits flexibility of the skin, which marine mammals rely on for swimming motions.
Of these theories, streamlining and reliance on blubber for insulation and temperature regulation seem to be the most compelling explanations for why narwhals do not retain the fur that grows in utero.
Fur serves an important role in insulation, temperature regulation, sensory information, and protection for land mammals. But for narwhals and other cetaceans that spend their entire lives submerged in water, fur impedes their hydrodynamic body shape, offers no temperature benefit, and can interfere with flexible skin and movement. Shedding all hair early in development allows smooth-skinned cetaceans like narwhals to thrive in their aquatic environment.
Narwhal Skin
A narwhal’s skin plays several important roles:
- Insulation – The thick blubber layer beneath the skin insulates narwhals from Arctic temperatures.
- Streamlining – Smooth, hairless skin reduces drag and allows narwhals to swim quickly with little resistance.
- Flexibility – Skin needs to bend and stretch over muscles and bones during swimming motions. Hair would restrict this flexibility.
- Sensory input – Skin contains nerves to provide information about pressure, temperature, pain, and touch.
- Protection– Tough skin acts as a waterproof barrier against the marine environment.
- Thermoregulation – Blood vessels in the skin help dissipate excess heat after dives into warm depths.
Narwhal skin is made up of three layers, similar to land mammals:
- The outer epidermis is composed of dense, waterproof keratin the same protein that makes up human fingernails, whale baleen, and animal hooves. It protects underlying tissue from scrapes, stings, salt, and dehydration.
- The middle dermis layer contains collagen fibers that give the skin strength and flexibility, as well as blood vessels, nerves, hair follicles, and glands.
- The inner hypodermis is made up of connective tissue and a thick insulating fat layer called blubber. This blubber layer can be up to 10 inches thick and helps narwhals maintain a warm, stable body temperature even in near-freezing Arctic waters.
The dermis and hypodermis contain nerves that provide narwhals with information about their surroundings. For example, free nerve endings detect temperature and pain. Hair follicle receptors sense vibration and movement of the hairs. Specific spots near the blowhole are especially sensitive to touch.
While narwhal skin lacks fur and hair, it serves many other purposes essential to the whale’s survival in the frigid Arctic environment. Smooth flexible skin optimizes swimming performance, while the thick blubber layer substitutes for the insulation fur would provide on land.
Skin Color and Patterns
A narwhal’s skin ranges in color from blue-gray to mottled gray. Calves are born with darker skin that lightens to a pale speckled gray as they mature. The speckles are due to small dark freckles that develop with age. These dark spots may help camouflage narwhals in the ocean depths. Often the dorsal (top) side of a narwhal whale is darker gray than the paler ventral (bottom) side.
Other unique narwhal skin traits include:
- Their famous spiraled tusks project straight out the left side of their heads through a pore in the skin.
- They have a notched tail or fluke with unique individual patterns that can help identify individuals.
- Scars from bites or deep scratches often accumulate on mature males from tusking competitions over mates.
- Some males develop warty bumps on their heads as they age.
These skin textures and markings help distinguish individual narwhals within their social groups. The patterns may also signal information to potential mates during the breeding season.
Mammalian Skin
As mammals, humans share the same three-layered skin structure with narwhals:
| Skin Layer | Narwhal | Human |
|---|---|---|
| Epidermis | Thick, tough keratin waterproofs skin | Keratin, melanin pigment |
| Dermis | Dense connective tissue with follicles, vessels and nerves | Fingerprint ridges, sweat glands |
| Hypodermis | Thick blubber layer insulates | Fatty subcutaneous tissue |
However, human and narwhal skin differ in many ways reflecting our vastly different environments. Humans have fine body hair, numerous sweat glands, and skin pigments that protect us on land but would hinder an aquatic mammal. While narwhal skin lacks insulation from fur or hair, it has adapted to insulate, streamline, protect, sense, and thermoregulate these whales in the Arctic seas.
Conclusion
In summary, narwhals do not have hair or fur covering their bodies as adults. Like other cetaceans, narwhals are born with some fetal hair or lanugo that falls out before or shortly after birth. Smooth, hairless skin reduces drag and allows narwhals to swim quickly in Arctic waters. Blubber provides insulation, eliminating the need for fur. While hair can serve useful functions for land mammals, it would only impede narwhals’ hydrodynamic needs as fast swimming specialized marine mammals. Shedding all hair early in development allows narwhals to effectively occupy their unique Arctic marine niche.
