Cold Feet: Why Don’t Penguin’s Feet Freeze?

Cold Feet: Why Don’t Penguin’s Feet Freeze?

by Sian Liversage

We all know that penguins endure and survive freezing temperatures in the Antarctic, these can range as low as -70˚C in the centre to -20 ˚C around the coast. Their bodies stay warm due to their insulating layers of blubber which lies just beneath the skin. However, their webbed feet are continually in contact with snow and ice, and yet somehow they manage to stay free from frostbite. So, it begs the question: Why don’t their feet freeze?

Penguins have special adaptations to keep their feet from freezing

Like many other species around the world, penguins have adaptations to avoid losing too much heat and to preserve a central body temperature. Penguin feet make it problematic to maintain that perfect body temperature of 40°C since they are constantly exposed to the elements; their feet cannot be covered with blubber or feathers like their bodies are, and together they create a large surface area exposed to the cold. But they need their feet so they can walk around the icy surface without slipping, and also so they can steer themselves when swimming.

A variety of penguins have developed behaviours that enable them to keep their feet warm. For example, Emperor Penguins hunch down so their bellies and feathers cover their legs, and they also rock back and forth onto their heels to lift their feet off the ice, therefore reducing contact time on the ground.

Penguins keep their feet from freezing not only behaviourally, but also through internal mechanisms

This is not the only way penguins avoid getting cold, however. They have evolved remarkable physical attributes too that make them perfectly adapted to their environment. There are two hidden mechanisms going on inside those legs and feet.

First, a penguin can control the rate of blood flow to the feet by varying the diameter of arterial vessels supplying the blood. During cold conditions, the flow of blood is reduced to hold onto heat. In winter, penguins will keep their feet a degree or two above freezing which reduces the chance of heat loss and avoids getting frostbite.

Chinstrap Penguins walking on the snow

And, of course, not all penguins live in places where their feet get cold

Not all penguin species live in freezing conditions though. Some species like Galapagos Penguins live in scorching sun and heat and thankfully their specialised heat exchange system also serves as a vital outlet for when their bodies become too warm. Blood vessels in the penguin’s feet expand, doing the opposite of what they do when they are cold. This allows an increase in blood flow, which in turn enables heat loss from the body. You may see penguins lying on the ground with their feet in the air and their flippers out to the sides to speed this process up and get rid of excess body heat.

Magellanic Penguins in the desert in Argentina

Humans can also do what penguins do with their feet (to some extent)

Penguin feet closeup

Close up of the bottom of a penguin’s feet

Amazingly, humans can also restrict blood flow to their extremities too. Our hands and feet will go white when they are freezing due to less blood circulating to them; blood is being redirected and prioritised to go to the core of the body where the vital organs will be kept warm. On the other hand, when we are warm our hands and feet will turn pink which is our body trying to cool us down. Controlling blood flow is very sophisticated and involves the hypothalamus, the nervous system and endocrine systems all working together to function properly.

Secondly, penguin legs work like a heat exchange system; blood vessels to and from the feet are narrow and woven closely together, which cools the blood from the body on the way to the feet and vice versa when the blood returns to the body. Therefore, their feet receive cool blood instead of warm blood, as this means less heat is lost while the body continues to maintain that toasty 40°C.

These adaptations show just how truly extraordinary penguins are; generations have survived the worst conditions nature could throw at them. These cold-adapted species live a challenging life, walking 100s of kilometres to feeding grounds, surviving snowstorms, and standing for weeks on ice while incubating an egg, and at the same time maintaining a warm body core temperature. Despite all these potential setbacks, their incredible feet and overall mechanisms to survive are still yet to be hindered by Mother Nature.

Penguins are amazing birds that have adapted ways to live in extreme environments. Have you ever seen some of these penguins in the wild? Tell us about it in the comments below. And please assist with our conservation projects and help us continue to provide you this information by donating to Penguins International.

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References:

Encyclopedia Britannica Blog. 2011. Penguin Feet: Avoiding Frostbite in the Antarctic. Webpage: http://blogs.britannica.com/2011/01/penguin-feet-avoiding-frostbite-in-the-antarctic/
How Stuff Works. 2019. Why Penguin Feet Don’t Freeze. Webpage: https://animals.howstuffworks.com/mammals/why-penguin-feet-dont-freeze.htm
New Scientist. 2006. Why don’t penguins’ feet freeze? And 114 other questions. P. 47-77

Martin Franklin In Blog

Penguin Record Breakers

Penguin Record Breakers

by Martin Franklin

At 100-130cm long and 22-40kg in weight, the Emperor Penguin is by far the largest of all the penguins. (This is, incidentally, only a little smaller than champion gymnast Simone Biles, whose height is 142cm and weight 48kg). But do the Emperor Penguin’s height and weight advantages translate into record-breaking penguin performances?

(1) Greatest Diving Depth – Emperor Penguin vs. Human

Alexey Molchanov holds the current human world record for the deepest single-breath dive (with fins, and without use of weights or inflation devices). He managed 130m. (Without fins, William Trubridge holds the record, at 102m). This equates to the Emperor Penguin’s preferred “average” dive depth, but it can easily dive to 400m, and has even been recorded at a depth of 564m. With a pressure at such depths of up to 30 times that at the surface, and no other penguins able to descend so deep, the Emperor Penguin is unquestionably the champion deep sea diver.^1,2

(2) Longest Time Spent Under Water for Emperor Penguins

The human record for this is currently held by Stephane Mifsud, who lasted 11m 35s. This, however, was stationary and in a shallow swimming pool, meaning his physical exertion was negligible, and he was unaffected by water pressure associated with water depth. Again, the Emperor Penguin beats this hands (or perhaps flippers) down: It prefers short dives of 3-6 minutes, but can stay under water for up to 22 minutes, which is longer than any other bird can manage.¹

Southern Rockhopper Penguins diving in the water

Southern Rockhopper Penguins diving into the water

(3) Fastest Swimming Speed of Emperor Penguins

The human world record holder in the 100m freestyle is Cesar Cielo, with a time of 46.91s, which equates to around 4.8mph (7.7kmph). The unofficial fastest recorded penguin to date (though others could be faster) is the Gentoo, at around 22mph (36kmph). That’s around 5 times faster than the fastest human.

Gentoo Penguins after a day of fishing

Penguins achieve these incredible speeds due to their unique anatomy, which includes:

A torpedo-like body shape (including legs placed far back on their bodies) which results in remarkably little drag (the legs only being used for steering when swimming);
Flattened and rigid wing bones, the arrangement of which (unlike in flying birds) create significant forward propulsion on both the up and down-stroke;
A silky outer layer of feathers; and
Heavy (non-pneumatic) bones, so the birds are not fighting buoyancy in the way flying birds would.

Penguins also have handy built-in “goggles”, meaning they can see well on both land and in water, as they possess:

Nictitating membranes (i.e. a transparent inner eyelids which can be drawn over the eyes);
Flat corneas (the transparent front part of the eyes), which reduce refraction (light changing course in different ways in different media); and
Strong focusing muscles (allowing them to change their lens shapes as required).^{1, 3}

(4) Competitive Eating (and Remarkable Egg-Care)

Penguins can eat an astonishing quantity of food very quickly, and their consumption increases markedly at particular times, i.e.:

Immediately before they moult (during a moult, which typically lasts a few weeks, they are no longer water-proof or able to thermo-regulate effectively, and thus cannot go fishing at sea);
When they have chicks to feed (which are fed regurgitated food);
In the case of Emperor Penguins, immediately before they start their long (up to 125 mile/200km) “march” to form breeding colonies. This is followed by the males taking on egg-incubation duties (which last for 62-67 days without food and in temperatures as low as minus 60^oC, unassisted by their female partners, and with only the body heat of other males with whom they huddle to help stay warm).

This feat of the Emperor Penguin breaks numerous records, including:

Being the only penguins to breed during the Antarctic winter;
This being the most intense cold experienced by any warm-blooded animal;
This being the longest continual incubation period of any bird (although kiwis and great albatrosses incubate for 71-84 days, they leave their nests to feed)²;
Males being able to regurgitate a protein-rich stomach secretion to feed their chicks for up to 10 days (if the females don’t get back to share chick-feeding duties in time);
Being the only birds (technically) never to touch land (as they generally form their breeding colonies on winter sea ice).¹

Adélie Penguins have been reported as able to eat 25g of krill per minute (which equates to around 0.5% of their body weight per minute).³This species has also been reported as eating around 800g of food per bird per day (which equates to around 16% of their body weight).⁴ In terms of weight alone (not calorific content), this is broadly equivalent to an average American man eating two 240g “Big Mac” hamburgers per minute, or 59 “Big Macs” per day.

Two colleagues tell me anecdotally that they once witnessed a chick-raising pair of Humboldt Penguins at ZSL London Zoo rival even the Adélie Penguins mentioned above. In just a few minutes, I am told that these birds (a female named Heidi and a male named Lars, pictured) each ate approximately 80-100 sprats (weighing around 840g). Given these penguins’ normal weights of around 4½kg each, this equates to them each eating around 19% of their normal body weights in one brief sitting.

Of course, Heidi and Lars were behaving naturally and appropriately, given their own nutritional requirements and those of their chicks at that particular time. I only wish I could claim a similar excuse myself in respect of my own occasional over-indulgences.

Lars and Heidi – Humboldt Penguins at ZSL London Zoo with (seasonal dependent) impressive appetites

Martin Franklin is a bird keeper at ZSL London Zoo, and works extensively with Humboldt Penguins. Any views or opinions expressed in this article are the author’s own, and do not necessarily represent those of ZSL

Penguins are amazing animals with even more amazing adaptions that help them live in extreme places. Like this story? Have a story of your own? Leave a comment below. And please help us to continue to provide you with penguin news articles by donating to Penguins International.

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References

¹De Roy, T., Jones, M. and Cornthwaite, J. (2013). Penguins: Their World, Their Ways. Bloomsbury Publishing: London.

² Lynch, W. (2007). Penguins of the World. A&C Black Publishers Limited: London.

³ Williams, T. D. (1995). The Penguins. Oxford University Press: New York.

⁴ Culik, B. M. (1993). Energetics of the Pygoscelid penguins. Habilitation thesis. University of Kiel.

Sian Liversage In Blog

Penguins in Captivity: Keeping them happy

Penguins in Captivity: Keeping them happy

By Sian Liversage

It seems that no matter what age you are, whether a child or an adult, one of the most popular and interesting animals to see when visiting a zoo or an animal attraction are the penguins. People have certainly anthropomorphised this species because of the way they look and behave; a good example of this is how they are often compared to a small human wearing a tuxedo. Their waddling gait, clumsy nature and charismatic personalities make them an ideal species to have in captivity, simply to bring the people in. But should they be kept in captivity in the first place?

There is definitely a balance to keeping penguins happy and healthy in captivity

We can’t hide the fact that there are some negative sides to life while living in the care of humans, especially if animals are mistreated or not appropriately housed. Penguins are no different when it comes to struggling in a captive situation.

In one facility, staff had to administer medication to their Humboldt penguins after they showed signs of stress attributed to the difference in local weather that was very different to their natural climate.

Stress can lower a penguin’s immune system, which could cause them to be more vulnerable to diseases, especially if they are kept in poor conditions. Enclosures that are small, with small pools, means that penguins cannot display their natural behaviours, which in turn will increase their stress levels. Another facility nearly ten years ago had several Humboldt Penguins die of infections from unknown causes. This could have been attributed to stress from living conditions or lack of staff knowledge, or any other number of reasons.

Despite the best intentions of an animal keeper, things don’t always go smoothly. For that reason, we promote AZA accreditation in the U.S. and BIAZA membership in the U.K. for facilities that meet strict guidelines for animal management and care. The standards held by facilities with this oversight will ensure the best care is given to all of their animals.

Animal care and management goes beyond best practices, however. The penguins need to be kept engaged and in an environment that promotes enrichment.

Zoo enclosures have advanced dramatically in keep penguins happy and healthy

Zoo enclosure designs have come a long way since the bare concrete space that animals used to live in, now providing an engaging, healthy sanctuary for penguins. Zoos and aquariums also play a key role towards conserving endangered species too, of which there are a large proportion of penguins under this category. Likewise, many zoos and aquariums aim to promote conservation work, educate the general public, and support wildlife projects. All of these categories merge to create a standard of welfare, which means that penguins which are kept in captivity are given the utmost care. These standards are in place to allow the animals to develop in a healthy environment as similar to their natural habitat as possible.

New enclosure designs promote more natural behaviours in penguins

The Detroit Zoo recognised that their penguins needed something more in their enclosure, so they replaced a 6-foot deep pool with a 25-foot deep pool. The penguins ended up spending extra time in the water than previously, showing the zookeepers that this new change enhanced their lives that much more. The penguins spoke and their keepers listened.

Flagship species, like penguins, will draw crowds in, helping to raise their profile. This will in turn fund conservation efforts to help protect the species in the wild. So, keeping them in an enclosure that promotes their natural behaviour is vital not only for giving them a stress-free life, but also for educating the general public on their behaviours and the conservation work that is ongoing throughout the world.

Humboldt Penguin stands on the edge of its pool. Photo found at: https://www.penguins-world.com/penguins-in-captivity/

No matter what evidence is put forward though, animals in captivity whether it be focusing on penguins or not, will continue to be a controversial issue that is widely discussed. From the evidence shown in this blog, it seems that as long as penguins can behave naturally, they are able to live a long happy life in a human made environment without predators. The efforts that zoos and parks will go to nowadays to keeping their animals stress free is astounding, and I think it’s safe to say that people have learned from the past and will continue to learn the needs of their animals for the future.

Pro/con, zoos are helping penguins feel like they are more in their natural habitats while in captivity, but they will always feel do better when free. Please help us continue to provide you this type of information by donating to Penguins International.

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References:

DW Made for Minds. 2017. Should penguins be an animal attraction? Webpage: https://www.dw.com/en/should-penguins-be-an-animal-attraction/a-38557239

Penguins World. 2017. Penguins in Captivity. Webpage: https://www.penguins-world.com/penguins-in-captivity/

In defence of zoos: how captivity helps conservation. 2016. Webpage: http://theconversation.com/in-defence-of-zoos-how-captivity-helps-conservation-56719

Nataly H. Aranzamendi In Blog

Why are we still lacking effective conservation measures for penguins?

by Nataly H. Aranzamendi

Penguins are in trouble. Despite being loved by people and being the target of large amounts of research, many penguin species are currently classified in an endangered category. In order to protect these amazing birds, penguin conservation efforts need to be initiated, strengthened and supported.

Penguin conservation is imperative!

More than half of the 18 penguin species are considered to be in decline and their populations have not recovered since penguin conservation efforts began¹. Even for those species that are showing positive signs of recovery, multiple threats still make their situation at jeopardy.

To discuss and underline which are the most immediate conservation needs to protect penguins, a group of scientists working with penguins, the IUCN Penguin Specialist Group, held a workshop and has published their most relevant conclusions¹. Following are some take home messages from this work.

What are threats to penguins?

Using a pairwise ranking approach, the scientists ranked penguins according to the most pressing global threats existing at the moment for all species. This approach gave a ranking of those species that needed more conservation and research.

Another ranking was done for those penguins that need the most urgent conservation measures and immediate political intervention. Either because they are species experiencing rapid population declines or species with extremely limited distribution ranges. Three species were at the top of the ranking: African Penguins, Galapagos Penguins and Yellow-eyed Penguins.

An Endangered African Penguin

Decreasing penguin populations

African Penguin populations have decreased since the early 1900s to only 21,000 pairs left. Their decline has been most likely caused by a lack of food as a byproduct of changes in climate and overfishing. Petroleum pollution and predation have had a major toll on this species as well. The IUCN Penguin Specialist Group has suggested that a network of Marine Protected Areas could offer protection for the majority of these birds, although the protection may not help during all life stages.

Galapagos Penguin populations have suffered extreme number fluctuations, in relation to El Nino events. This species can skip breeding when food is scarce. That, in combination with limiting cavities for breeding, and the presence of invasive predators, has vanished any hopes of quick recovery. For this penguin with a very limited geographical range, the management of fisheries is crucial, since it will guarantee food at tough times. At the moment, less that 1% of the marine reserve around Galapagos is closed to fishing.

The Yellow-eyed Penguin has suffered steep declines and currently only 1,700 pairs are left. This species faces several threats: introduced predators, environmental change and interaction with humans and fisheries. Managing these threats in conjunction could offer better perspectives for their future.

Endangered Galapagos Penguins

An Endangered Yellow-eyed Penguin

Marine Reserves are the most powerful tool for penguin conservation

From all the measures discussed by the group of specialists, Marine Reserves were ranked as the most valuable tools for conservation existing to date. The creation of such reserves will allow management of several threats simultaneously, including those threats created by direct interaction with humans (i.e. tourism).

But why has penguin conservation not moved faster in the last decades? The group agreed that most of the limitations are in relation to the penguin’s biology and funding problems.

Penguins are colonial long-lived species that can potentially move beyond a country’s boundaries. This means that to effectively study them, long-term funding to follow individuals throughout their lives and international collaboration at many levels are needed. Such factors constitute the most limiting issues at the moment.

Lack of long-term funding does not allow long-term monitoring of most populations. Moreover, due to practical reasons, most penguins are monitored only when they breed, leaving gaps of information about what they do in the non-breeding season.

The non-breeding season, as well as the juvenile stage, are key elements to monitor, since it is at those stages that increased mortality occurs, which eventually would have consequences for population trends.

Effective protection of international waters is also an issue. At the moment, only 2% of the ocean is protected, while the goal established by international agreements is to reach 30% of ocean protection. A goal that seems unreachable right now.

To successfully protect penguins requires collaboration and communication between stakeholders: groups of scientists, legislators, NGOs, fisheries and local population. Without such collaboration, any ambitious conservation goal for penguins will not be reached.

Action to protect our treasured penguins is needed now, because penguins are running out of time. It has become everyone’s work to take action for the penguins and their future.

As you can see, there’s still a lot of work that must be done to protect and conserve penguins. Please assist with our own conservation projects and help us continue to provide you this information by donating to Penguins International.

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References

Boersma, P. D., Borboroglu, P. G., Gownaris, N. J., Bost, C. A., Chiaradia, A., Ellis, S., … & Waller, L. J. (2019). Applying science to pressing conservation needs for penguins. Conservation Biology 10.1111/cobi.13378.

December 2019