Tales from Tanzania: So, why do zebras have stripes, like, for real?

Today we saw dozens of very photogenic zebras. This got David and me talking: What came first, the zebra or the stripes?

baby Zebra

There are plenty of theories as to why the zebra has stripes – some more fantastical than others.

According to one African tale, the zebra was once pure white. One very hot day, the zebra went down to a watering hole to drink, but the watering hole was being guarded by a baboon bully who didn’t want to share. The zebra and the baboon got into a fight over the water and during the course of the fight, the zebra backed into the baboon’s fire and tripped. The hot branches left black scorch marks on the zebra’s hide.

While that tale, and others like it, are certainly fun to hear, they aren’t terribly scientific. So what says science?

One popular theory posited is that the stripes act as camouflage, but zebras graze in the open in relatively short grass. The stripes aren’t really making them blend into much of anything.

Another theory is that the stripes make it harder for a predator to pick out an individual from the group. Scientists originally believed that the stripes, when viewed at a distance, would simulate heat waves. Thus, that close-up would be confusing, because all the zebras would blend together. In reality, lions are the main predators of zebras and they generally hunt at night. A zebra’s stripes would, in fact, make them more distinct and visible in the moonlight.

The flip side of this theory says that the stripes help zebras recognize individuals in the larger group. This is actually supported by research, which shows that captive zebras prefer standing next to a patterned wall rather than a solid colored wall, but not 100 percent understood.

A relatively new theory that seems to have some merit is that the zebra’s stripes make excellent fly repellant. Cattle (and zebra too) are more susceptible to illness caused by the tsetse fly, which bite as a reaction to movement and dark colors. In fact, the tsetse fly prefers to bite through dark clothing even when a light, bare arm is available.

To test this theory, one study looked at horsefly bites on horses. They set up five “targets” for the horseflies — one black, one white, one grey, one with horizontal stripes and one with vertical stripes. The great target and the target with the vertical stripes had the least number of bites.

Why? The horsefly, like most insects with compound eyes (including the tsetse fly) has the ability to see polarized light. This improves their ability to see solid and dark colors, allows them to “see” heat signatures and enables them to track moving objects (especially dark ones). Because of these specially adapted eyes, the zebras’ stripes would make them disorienting to the horsefly. The stripes, hypothetically, break up the shape of the zebra and make it harder for the fly to focus in to bite.

While this all sounds great in theory, scientists haven’t conducted these same tests on actual zebras in Africa, but they are pretty positive the results would be the same.

Kwa heri ya kuonana!

Tales from Tanzania: Hunting the “little” Big Five — with a camera lens

The safari, which literally means “journey” or “voyage,” began when Europeans traveled into Sub-Saharan Africa. They came to observe and record the flora and fauna of Africa, but the tales of the unusual animals brought other travelers — those in search of adventure and danger. Originally when one went on safari, one went to hunt the Big Five: lions, leopards, rhinos, elephants and Cape buffalo, ranked not by their size but by their difficulty to hunt on foot.

The modern iteration of the safari still has shooting, but now it is from behind the lens of a camera rather than down the barrel of a gun.

While Dave is excited to see and shoot the Big Five with his camera, I am more excited to see the “little” Big Five, as I am calling it. These are some of the biggest, baddest invertebrates on the African continent. Though they are (relatively) small, they can be fierce!

1. Siafu Ants (Genus Dorylus)

Siafu, also known as Driver or Army Ants, can live in colonies of up to 20 million individuals. When there is a food shortage, the ants will leave their hill and form marching columns of up to 50 million ants, traveling at about 70 feet an hour and destroying everything in their path. While they can be dangerous if an animal comes in contact with these traveling columns, they also perform an important service: pest control. The ants literally drive (hence the name) all other animals, pests and people alike, away from their homes.

Another weird fact: These ants have incredibly strong jaws. In fact, you can break off their bodies and leave the head without the ant releasing its hold, so they are often used as a natural emergency suture which will hold for days.

2. Giant African Millipede (Archispirosterptus gigas)

H_orig_millipede

Over 15 inches long and 2.5 inches around, the Giant African Millipede is one of the biggest and most recognizable invertebrates around. Despite its name, millipedes don’t really have a thousand feet. They actually have around 256 feet (four legs per body segment multiplied by 64 segments on average = invertebrate math). In general, millipedes can make excellent pets but many species come with a slightly unusual side effect: when irritated, they secrete a cyanide-based compound. To humans, the secretions are only mildly problematic, usually resulting in discoloration or mild irritation of the affected skin. However, these same secretions can burn the eyes or exoskeletons of ants and other predators. In the case of the Giant African Millipede, their secretions taste and smell really bad and so it makes them unappetizing to predators.

Another weird fact: Millipedes have a symbiotic relationship (try finding that as an option for your Facebook status) with tiny species-specific mites living on them. The mites keep the millipedes clean and tidy and the millipedes give the mites snacks and a place to live.

3. Ghost Mantis (Phyllocrania paradoxa)

ghost

All right. At 1.5 to 2 inches, these guys aren’t that big — but they are that awesome. Their superpower? Their camouflage. Ghost mantises are excellent little mimics. Living in dry areas on bushes and shrubs, the ghost mantis looks to all the world like a brown, dried leaf — even going so far as to rock back and forth slowly so they look more like a leaf blowing in the wind. As vicious little predators, their incredible camouflage helps them ambush unsuspecting prey with their spiked, raptorial forelegs.

Another weird fact: The closest living relatives to the mantid family are termites and cockroaches, both in the order Blattodea. All three had a common ancestor but developed independently.

4. Giant Walking Stick (Bactrododema episcopalis)

Just like the name suggests, this big bug looks to all the world to be a branch from the tree in which it hides. Stick insects are part of the Phasmid order, which comes from the Greek word “apparition.” They are aptly named as they can seem to appear from nowhere due to their ability to blend in. Although herbivorous, stick insects aren’t defenseless. Some species have spines on their legs, while others can spray irritating liquids at attackers. Yet others will regurgitate a nasty substance that will put a bad taste in a hungry predator’s mouth or reflex bleed, oozing a foul-smelling hemolymph from joints in their body. The giant walking sticks in Tanzania will average around a foot in length, but there is a species in Borneo that has been recorded at an incredible 22 inches.

Another weird fact: Some stick insect species can reproduce parthenogenetically (that’s a fancy word that means “without males”). A captive female stick insect can produce hundreds of all-female offspring without ever mating. In fact, there are some species of stick insects for which scientists have found no male specimens.

5. Goliath Beetle (Goliathus albosignatus, Goliathus orientalis)

goliathus_orientalis_preussi_1
I saved the best for last.

I love beetles and not only do they have cool beetles in Tanzania, they have two species of one of my favorite beetles: the Goliath. These big, bad beetles can grow up to 4.5 inches long and 3.5 ounces in weight — about the same size, weight and shape of a box of regular, powdered Jell-O. Incredibly strong for their size, these burly bugs can lift up to 850 times their own body weight. For the average 200 pound man, that’s the equivalent of lifting 77 tons!

jello

Boxes of Jell-O. In case you weren’t sure what those looked like.

Another weird fact: Beetles comprise the largest order of insects, Coleoptera, with 350,000 to 400,000 named species. This makes up 40 percent of all known insects and 30 percent of all known animals.

You know what’s even cooler? Scientists estimate that there could be 750,000 to 4,000,000 species of beetle that haven’t been named or discovered yet!

While I can’t be certain that I will get to see any of these critters in the wild on our trip, I am certainly hopeful that I will be able to return with photographic evidence of our encounters! Check back with Dave and I in early December and we will share some of our best photos from the trip.

What’s the over you’ll make it Down Under? Final chance to book a trip to Aussieland for a rare eclipse

It’s your final chance to get in on the trip of a lifetime (or at least the next several years) to Australia and New Zealand.

Cairns, AustraliaThe only total solar eclipse of the year is viewable on land only from the northeastern coast of Australia. The Museum has secured hotel space in Cairns for the rare eclipse and planned a trip around the voyage with an optional extension to Fiji.

Led by Dr. Carolyn Sumners, HMNS’ VP of Astronomy, the two-week tour of the South Pacific includes Cairns and Sydney, Australia as well as Christchurch and Queenstown, New Zealand and an ideal eclipse viewing spot on the coast of Australia near the Great Barrier Reef.

What: South Pacific Wonders and Solar Eclipse
When: Nov. 10 through Nov. 24
Where: The other side of the world

For more information on booking, email travel@hmns.org or call 713.639.4737. Click here for full itinerary and pricing.

Note: heat from active volcano may damage running shoes.

at the base of the volcanoRecently I went on a trip to Antigua, Guatemala and had the opportunity to go to the top of an active volcano just a short distance away from the city called Pacaya. One of the main reasons we chose to visit Antigua was the proximity to active volcanoes because ever since I saw the Ring of Fire IMAX when I was a child I have been fascinated by volcanoes and lava.

So we reserved our spot to go to the volcano and they gave us a slip of paper that told us to pack snacks, water, a flashlight (we signed up for the afternoon/night hike) and wear running shoes or hiking boots. The tour group picked us up at our hotel and we were off for our one and a half hour ride in a van packed with people on winding roads – for a girl like me who gets a little car sick, keeping the window cracked was important on this drive.

When we arrived at the base of the volcano, we were immediately met by the children who live in the village at the base of the volcano, with hands full of walking sticks and “ponchos” telling us to buy these things from them.  The “ponchos” mostly turned out to be garbage bags but it was rainy and the thought of a long hike in the rain for those in our group who did not bring rain gear probably made garbage bags look like a reasonable idea! The children demonstrated how sturdy and good their walking sticks were and said “stick for you?” One man (pictured) did not want a stick but this little boy followed him for about the first 10 minutes of the hike. You might also note that this man was not wearing appropriate footwear – socks and sandals seem like a very bad choice on a rainy day up a volcano – but maybe that’s just me.

Our guide told us that the trip to the top of the volcano was going to be at most 1 hour and 45 minutes. The rain decided to stop a few minutes into our trip so we were able to pack up our rain gear and continue on our journey. The first hour or so of the hike was on steep, narrow dirt paths in the forest; as you can imagine it was pretty muddy after the afternoon rain. It was at this point that I knew it was going to be my fate to have very muddy pants before our ride home. With no lighting along the path the journey back down the volcano was sure to be a slippery adventure.

With about 30 minutes left in our trip up to the top we walked out of the forest and the landscape changed completely – suddenly there were no more trees or life of any kind – only black lava rocks as far as the eye could see. The path we took across was mostly made of tiny tiny rocks, which is very much like trying to climb uphill in a sandpit or on a treadmill – you use a lot of energy without making much progress. The altitude change made it harder to breathe and I kept having to take little breaks, but with a glowing river of lava in sight it was definitely no time to quit.

When we reached the top, the heat radiating from the lava beneath the thin crust of cooled lava felt a lot like the beginning of a sunburn on my skin. We used our trusty sticks to tap the surface in front of each step to be sure the crust would not crack beneath our weigh – sometimes the tap would cause a whole patch of crust to fall in – yikes! Certain cracks exposed glowing lava flowing beneath – it was incredible! I’m including some photos below but I realize now it’s pretty difficult to get the sense of the lava flowing from any of the photos – but believe me – it was an awesome experience and I would recommend it to anyone who has the opportunity to see an active volcano up close. It was completely worth the wacky van ride and trying uphill journey!

A WORD OF ADVICE FOR ANYONE INTERESTED IN TAKING THIS TYPE OF JOURNEY – When we made it back to the bottom of the very muddy mountain in the dark of night (and yes, I did manage to slide down a bit of the trail on my rear end) I realized that my running shoes were a slightly different shape! The heat of the surface near the flowing lava heated the puffy layer of rubber in the soles of my shoes and as I tromped down the mountain the softened layer shifted and my shoes were newly lopsided. Perhaps hiking boots would have been a better choice. Oh well, I guess you learn something every day! Also, note that the stick you may “purchase” at the bottom of the volcano will likely be more of a “rental” when you return to the bottom and the same children who 3 hours earlier had sold you the stick will be welcoming you back to the village by saying “stick for me?” It probably wouldn’t fit in your luggage anyway.


there are a lot of rules when visiting Pacaya.

There are a lot of rules to know about when visiting Pacaya!

A diorama of the volcano and our path up to the top.  

I was laughing while sliding backwards down the slope trying to pose for this one!

look! that's real lava glowing under there!!

Look! That’s real lava glowing in there! It was very interesting to see the folds of the surface of the cooled lava flows.

one place I decided it would not be safe to step...

One spot I tapped with my walking stick and decided not to step.

This guy in our group was close enough to the river of lava to set his walking stick on fire – it was incredible!

Our guide brought a bag of marshmallows to the top and handed them out so that people could roast them over the lava.