Can Newts Breathe Underwater?

Newts are fascinating amphibians that live both on land and in the water. If you’ve ever caught one of these little salamanders in a backyard creek, you may have wondered how they are able to survive in both environments.

Specifically, you might be curious whether newts are able to breathe underwater like fish, or if they need air from the surface like we do.

If you’re short on time, here’s a quick answer to your question: Yes, newts can breathe underwater thanks to special structures and adaptations that allow them to absorb dissolved oxygen from the water.

In this comprehensive article, we’ll take a deep dive into newt physiology and behavior to understand exactly how they are able to pull off their amphibious lifestyle. We’ll explore the unique structures newts use for underwater breathing, compare newt respiration to other amphibians, and shed light on how important access to air is for their survival.

Whether you’re an amphibian enthusiast or just generally fascinated by nature, you’ll find the answer to how newts breathe underwater below.

Newts as Amphibians

Taxonomy and characteristics of newts

Newts belong to the family Salamandridae and are a type of salamander. There are around 66 known species of newts found in North America, Europe, North Africa, and Asia. Some key characteristics of newts include:

• Smooth, moist skin: Newts need to keep their skin moist in order to breathe properly. Their skin is not covered in scales like fish or reptiles.
• Semi-aquatic lifestyle: Newts spend part of their life cycle in the water and part on land. They have adaptations for both environments.
• Unique lifecycle: Newts undergo metamorphosis, starting as aquatic larvae (with gills) before developing into air-breathing terrestrial adults.
• Ability to regenerate limbs and organs: Newts are famous for being able to regrow lost limbs or damaged organs over time.
• Toxic skin secretions: Many newt species secrete toxins from their skin as a defense against predators. These toxins can be quite potent.

In terms of taxonomy, newts belong to the order Caudata along with other salamanders. There are three main newt families:

• Salamandridae – True newts and fire-bellied newts. Found worldwide.
• Plethodontidae – New World slimy salamanders. Found in North and Central America.
• Proteidae – Olms. Found in southern Europe.

Well-known newt species include the fire-bellied newt, Spanish ribbed newt, smooth newt, and common newt. Newts range in size from just 2 inches long to over 12 inches for the largest species!

Differences between newts, frogs, and salamanders

While newts are grouped under the broader category of salamanders, there are some key differences between newts, frogs, and other salamander species:

As shown, newts and frogs both undergo a metamorphosis from an aquatic larva to a terrestrial adult. However, newts retain a more semi-aquatic lifestyle as adults. Newts also have toxic skin secretions, unlike frogs.

Compared to other salamanders, newts are generally more aquatic throughout their lifecycle.

The unique traits of newts, such as metamorphosis and limb regeneration, have made them important model organisms in biological research. Their diversity and adaptable nature continues to fascinate biologists and nature enthusiasts alike!

Newt Respiration

Cutaneous respiration

Newts have the remarkable ability to breathe through their skin, a process called cutaneous respiration. Their thin, moist skin is rich with blood vessels, allowing dissolved oxygen to pass easily from the surrounding water into the bloodstream (Smith 2021).

This allows newts like the Eastern newt (Notophthalmus viridescens) to remain submerged for extended periods without drowning. In fact, some newts absorb 85-90% of their oxygen requirements this way, only relying on their crude lungs or buccal pumping occasionally (IUCN 2022).

Buccal pumping

When underwater, newts also use a process called buccal pumping to supplement cutaneous respiration (Clarke 1977). This involves rhythmically pumping their buccal cavity (mouth and throat) to flow water over the thin mucous membranes, which extract further dissolved oxygen.

Newts can alter the frequency of buccal pumping depending on oxygen demand and availability in the water (Lenfant and Johansen 1968). So in oxygen-rich water, buccal pumping may provide up to 21% of respiratory requirements, whereas in oxygen-poor water this figure may exceed 50% (Boutilier et al.

1979).

Gills and blood vessels

While primarily cutaneous breathers as adults, larval newts (and some paedomorphic species which retain juvenile traits) have prominent external gills for aquatic gas exchange. For example, the Japanese fire belly newt (Cynops pyrrhogaster) retains its red feathery gills lifelong.

Most newts resorb their gills as they metamorphose into air-breathing juveniles. Nonetheless, newts tend to have extensive blood vessels and capillaries throughout their skin for efficient oxygen uptake (Duellman and Trueb 1986).

This network includes blood vessels in the membranous tissue lining the mouth and cloaca. So newts can supplement oxygen intake through the linings of these openings when underwater or during periods of high activity or stress.

Newt Adaptations for Underwater Breathing

Highly permeable skin

Newts have skin that is highly permeable to gases, allowing them to absorb oxygen directly from the water through their skin (cutaneous respiration). When underwater, newts rely heavily on cutaneous respiration to get the oxygen they need.

Their thin, moist skin lacks scales and has a large surface area, making it an effective respiratory organ in water. Studies have shown that some newts can absorb around 85% of the oxygen they need when submerged through their skin alone!

Ability to absorb dissolved oxygen

Not only can newts breathe through their skin, they can also absorb dissolved oxygen from the water using the tissues in their mouth and throat region (buccopharyngeal respiration). Specialized cells and blood vessels in the mucous membranes allow for gas exchange.

While less efficient than cutaneous respiration, this adaptation gives newts an extra way to get oxygen when underwater without needing to surface.

Cardiovascular adaptations

Newts have adaptations that allow their cardiovascular system to function even when they are submerged. For one, newts have lower blood pressure than other land animals, which prevents excess fluid from filtering out of their blood and into the surrounding water.

Their blood cells also have more oval shapes, allowing blood to circulate even when oxygen levels are low. Another key adaptation is their ability to vary blood flow to different parts of their body depending on need – for example, redirecting blood away from digestive organs and towards skin and respiratory surfaces during long dives.

Together, these remarkable cardiovascular modifications allow newts to successfully meet the oxygen demands of their tissues when under water, sometimes for extend periods of over a day!

Importance of Access to Air

Time limits for underwater breathing

Newts have lungs and breathe air just like humans, so they cannot stay underwater indefinitely without access to oxygen. Their underwater breathing limits vary by species, but generally newts can hold their breath for 30-40 minutes.

This gives them enough time to forage for food, avoid predators, and find mates in their aquatic habitats. However, they must eventually surface to gulp air before returning below the water.

Some important factors impacting newts’ underwater endurance include:

• Body size – Smaller newts have lower oxygen needs.
• Water temperature – Colder water contains more dissolved oxygen.
• Activity level – Moving around uses more energy and oxygen.

When a newt’s oxygen stores run low, it will become stressed and have to surface quickly. Prolonged oxygen deprivation can be fatal. So while newts are well-adapted for aquatic life, access to air is still critical for their survival.

Vulnerability to oxygen deficits

Newts face high risks if unable to reach the water’s surface to breathe. Oxygen levels get depleted rapidly during underwater activity. Newts’ metabolism depends on a steady oxygen supply to power muscles and maintain cell function.

After using up internal oxygen stores, newts become desperate to take a breath.

Dangerous situations that can limit newts’ air access include:

• Accidental entrapment under debris or mud.
• Thick ice or plant cover blocking the water’s surface.
• Water oxygenation problems due to pollution or algal blooms.

Without the ability to surface, newts will start to suffocate within minutes as oxygen debt builds up. This leads to loss of consciousness and death shortly after. Newts’ high vulnerability to hypoxia helps explain why they seldom stray far below the water’s surface for extended periods.

Surfacing behaviors

When in need of air, newts will immediately swim straight upwards towards the water’s surface. Some signs a newt is about to take a breath include:

• Bottom-sitting followed by a vertical rush upwards.
• Gulping motions as the head tilts back with mouth agape.
• Taking breaths at more frequent intervals.

Upon reaching the surface, newts will gulp air while floating with their heads out of the water. Their skin is highly permeable so some cutaneous respiration may occur as well. After catching their breath, they dive back down below the surface.

Newts utilize air bubbles trapped against their bodies to prolong underwater time when oxygen runs short. They have also been observed performing aquatic surface respiration, positioning their bodies vertically to gulp air from a miniscule air-water interface layer.

Understanding newts’ surfacing behaviors provides insight into their dependence on aerial oxygen intake despite living largely submerged. The quest for air is an ever-present factor influencing newts’ activities and habitat preferences.

Conclusion

As amphibians, newts have evolved fascinating adaptations that allow them to survive both on dry land and in underwater environments. Through structures like permeable skin, feathery external gills, and modified blood vessels, newts can effectively absorb oxygen from water, granting them the ability to breathe underwater for extended periods.

However, newts do require occasional access to atmospheric oxygen to replenish their air supply, so they cannot spend their whole lives fully submerged like fish. Their amphibious nature gives them the best of both worlds – access to food and shelter in the water, along with the breathing advantages of surface air.

The next time you see a newt paddling along the floor of a pond or lake, you can take a moment to appreciate the remarkable physiological tools it employs to pull off its aquatic feats. Nature has crafted in newts an elegant solution to surviving in two very different realms.

After learning how they breathe, we can agree the answer is a definitive yes – newts can indeed breathe underwater!