Meredith: Why are reptiles, cold-blooded animals, able to survive in arid environments?
Peter Gros: Well, that's a very good question. And that is because they (for instance, crocodiles) can live for many months without water and food if necessary. They can find larger bodies of water that haven't dried up, and then they might migrate at night over land when it is cooler. They might dig burrows in the mud or sand or the overhanging banks, but the real clue is estivation. It's similar to hibernation for animals that don't need to create body heat. It's the manner in which reptiles can save energy in order to survive in a hostile environment where there is little available food or water. Reptiles also learned to dig burrows in the sand during the heat of the day and optimize their surface areas, as we saw tonight, by facing the sun to warm their bodies.

Carrie: Do most deserts have a lot of animal life, or is the Namib unique?
Peter Gros: The Namib Desert is unique because of the fog. In the time that the night fades and the sun creeps toward the horizon, warm air from the Atlantic Ocean sweeps over the cold waters at the Benguela Current. This combination of opposites creates thick coastal fog that penetrates as far as 60 miles inland. These fogs and the fresh water are the life essence of the Namib Desert. Moisture condenses on desert grasses. As you witnessed tonight, these sparse drops of dew must sustain many of the small-bodied animals until the next day, when dawn returns.

Tracy: Where do they get their water?
Peter Gros: In many ways. Some animals, like the tenebrionid beetle, have adapted by head standing or fog basking — collecting fog, and collecting 40 percent of their body weight in moisture. Others collect their moisture from the grasses and the plants in the mid desert. Still others, like the lizards we saw, collect most of the moisture they need from the animals they consume. It seems most life in the mid desert has been designed for the collection of moisture, like the wonder plant called the Welwitschia Mirabilis. It's endemic to the mid desert and lives 1,000 to 1,500 years. The key to that is that the leaves are apparently able to drink up fog water and deliver it to the roots extending 3 meters into the ground. Other lichens are believed to live in the mid desert for thousands of years.

Barry: What animal in the desert is your favorite?
Peter Gros: I would say the elephants, having spent so much time around desert elephants learning from their amazingly high level of intelligence, their parenting skills and their matriarchal society, which shares the knowledge of where to find water and food and passes it from generation to generation. Knowing they live in a desert climate needing hundreds of gallons of food and water every day to survive, dusting their backs to prevent sunburn, herding their babies within the shade of their parents, and continuing to flourish in this harsh environment has always amazed me.

Gene: What kinds of snakes inhabit the Namib Desert?
Peter Gros: The snake that seems to be the most well adapted is the sidewinder, which reduces contact with the hot sands with its peculiar movements sideway as a form of locomotion. We are always on the lookout for them, since most snakes feel the vibration as you plod along and disappear. Adders lie still and don't move or make any sounds until the last second, when they make a puffing noise. There are more snake bites from snakes in the adder family in that area of the desert than any other.

Jessica: How do animals like the Grant's golden mole and the shovel-snouted lizard breathe under all that sand?
Peter Gros: The sand has pockets of air trapped, and the shape of the mole also creates a pocket where they can breathe. The golden mole is the only completely blind mole that I am aware of. However, farther inland in the Kalahari there are many kinds of moles, mice and rats. I awoke one morning, after having had an energy bar before going to sleep in my sleeping bag, to find a mole cleaning my moustache for me. It was quite a rude awakening, since our guides explained that some of these animals carry the plague. Needless to say, I washed my face more thoroughly the next night!

Lisa: How do the Cape fur seals defend themselves against the black-backed jackals? Can they?
Peter Gros: The large numbers of fur seals together act as a protectorate. Most importantly, the females identify their babies by the sounds they emit and will hover over them and herd them very close to their bodies, making bluff charges and threatening sounds toward jackals. This isn't always effective, since there can be hundreds of baby fur seals at one time and jackals, like wolves and many other canines, will hunt in packs.

Laura: Why do you think insects like the beetle, spider and ant are able to survive in the Namib?
Peter Gros: Because they have adapted to the severe dichotomous climate. For example, the tenebrionid beetle, over the centuries, has been starting to grow additional hair on the bottom of its legs to get them higher off the hot sand. A couple of inches off the hot sand can mean the difference between life and death. The ants are aided by sheer numbers and their ability to be both plant-material eaters as well as carnivores. In our story tonight, we saw often how one animal becomes a food source for another. And although it's not always a pleasant cycle to try and understand, it reminds us vividly how in nature all living things are connected. The idea of losing species of animals will affect all the others who are dependent on the magnificent balance that we have in nature.

Liz: I'm curious about the shovel-snouted lizard. How does its shovel-shaped nose help it survive in the desert?
Peter Gros: It is shaped like a digging implement to make it relatively easy for it to burrow into the sand as it needs to cool itself. It has the shape of a plow and is able to break the surface of hard soil. Often the sand is loose and shifting, but depending on whether you are on the windward or leeward side of a large sand dune, the sand can be very crusty. You need something slightly pointed to break the surface and burrow. Also it's a handy tool for digging up escaping insects.

Leelou: Why doesn't the tenebrionid beetle get overheated? With its black shell, I would think that would only add to the heat problem that the animals must have.
Peter Gros: That is a very good question, because darker colors do retain more heat. But they are out there during the early-morning hours collecting fog that runs off their hard shells. The shell also acts as a protective armor, as it gets below the sand during the hottest point in the day.

Melanie: How does the Namaqua chameleon's skin help it stay cool?
Peter Gros: The armor-plated skin protects it against the relentless barrage of sand. The chameleon spreads its flank to right angles to the morning sun for maximum exposure. For midday heat, these chameleons shift their skin to a very bright reflective white. They also narrow their bodies and align them in the direction of the sun.

Kayla: How do the animals walk across the hot sand without injuring themselves?
Peter Gros: Some animals simply move very quickly, so their feet aren't in contact with the hot sand long enough to injure them. Others, like the chameleon we saw tonight, lift their feet every couple of seconds to cool them. Others, like the snakes, make contact with the sand and the smallest portion of their body possible. And many of them simply burrow under the sand during the hottest time of the day. It can be approximately 10 to 15 degrees cooler just inches under the sand.

Ted: Where do the non-meat-eating wildlife get their food from?
Peter Gros: If there is a short rainy season (and some years there isn't any), old riverbeds will start to flow, grasses will spring up farther north, a variety of acacia trees will start to grow and the desert will come to life. Desert animals are not particular about whether their food is lush or green or brown; as long as it is vegetation, in most cases, they will eat it. As we go farther north into Namibia, there is more underground water near the surface that antelope and elephants tend to find in the valleys between the dunes.

Bree: What does it mean when a snake has "dorsally placed eyes," and why does this help the snake to survive?
Peter Gros: It helps a snake to survive if he can bury his entire body just below the surface of the sand with just the very tops of his eyes exposed, where he can lie motionless awaiting prey. Some snakes will wait weeks for their next meal.

Black Cobra: Why doesn't a sidewinder move straight like other snakes?
Peter Gros: For two reasons: It is easier to climb a steep, moving sand dune sidewinding, but most importantly, only a small portion of the snake's body is in touch with the hot sand for just a split second. They prefer not to be moving on the hot sand. They are most active after sunset. They don't have to be fast, since their perfect camouflage will enable them to be very close to the prey before ambushing it.

Black Cobra: So what does a sidewinder actually eat?
Peter Gros: Mice, other small terrestrial mammals, ground birds, lizards, toads and, occasionally, other snakes. The adder will bite its prey and then follow its scent by flicking its tongue until it dies, and then it consumes it. They pack a potent cytotoxin that attacks tissue and blood cells. Many of these snakes can go six to eight weeks, sometimes longer, between meals.

Jennifer: Is the adder featured in the show venomous? What else does it eat besides lizards?
Peter Gros: Yes, it is a highly venomous snake. It has a potent cytotoxin that attacks the tissue in blood cells. I have never picked one up and never will try, but I have a tremendous amount of respect for any animal that can survive in the desert dune climate.

Nay Nay: Is it true that the mole doesn't have eyes? How does it survive without being able to see?
Peter Gros: Grant's golden mole actually has eyes, but it is blind because they are covered with skin and fur. It survives by digging in the desert sands for termites, ants, beetles, spiders and lizards. Sand is also found in their stomachs, which scientists believe aids in digestion. But to better answer your question, sand is a wonderful, terrific conductor of sound. As the mole burrows, it picks up the vibration from grasses blowing in the wind, and where there are grasses blowing in the wind, there will be moisture collected on them. The moisture is funneled to the roots, which attracts termites, ants and other insects that the golden mole loves to dine on. They are nocturnal and burrow into the sand during the heat of the day. They make shallow tunnels in the sand that collapse as soon as they are made. They are certainly one of my favorite desert animals.

Nancy: What are the temperature ranges during the different seasons between night and day?
Peter Gros: They range drastically, depending on whether you are near the coast or inland. It stays very cool near the ocean, which is why the fur seals we saw are so comfortable with all their fat for insulation and thick fur in the driving 50-mph winds and, of course, the cold ocean water, where their food is plentiful. Farther inland from the coast, the temperatures can vary from almost freezing to 130 degrees Fahrenheit during the heat of the day.

Animal Planet: Thank you for this informative chat! Unfortunately, we are almost out of time. Do you have any parting words for us?
Peter Gros: I'd just like to say thank you for all of your wonderful questions. I have enjoyed chatting with all of you, and I look forward to our next visit. You might chat with a friend this week and think of one thing that you can do to help preserve our natural world—locally, nationally or internationally.

Animal Planet: Thanks for joining our live chat. We hope that you enjoyed learning more about the animals of the Namib Desert.

Thanks again for joining us.

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