Are Those Hippos Sweating Blood? -- Hippos spend hours submerged up to their nostrils in tropical rivers because their thin skin is highly susceptible to sunburn. They do, however, like to spend time basking on sandbanks (or may not be able to fully submerge their 1-ton-plus bodies). Either way, when skin is exposed like this, the hippo's subdermal glands release a reddish secretion that keeps the skin moist and protects the hippo from U.V. damage. Due to the color of this secretion, it was once thought that hippos sweated blood. It has been suggested that these secretions also have extremely effective antibiotic properties, given that the wounds inflicted during fights seldom become infected, despite the less than savory conditions of the tropical waters in which they spend their days.

Is That Lion in Our Camp? -- If you hear a lion roaring at night (and, no doubt, you will), there is no need for concern, even if it sounds as if it is relatively nearby. A lion's roar can reach 115 decibels and is carried across the plains 5km (3 miles) or more; if you're close enough, you will feel your entire body vibrate. It is thought that both females and males roar to advertise their territory ownership to rivals of the same sex and possibly to recruit aid from distant companions.

The Mystery of the Disappearing Wildebeest -- There are a number of theories about why the zebra has evolved its stripes, but perhaps the most interesting is that posited by Dr. Tony Sinclair, long-time mammal researcher in the Serengeti. Using night-vision goggles to study the nocturnal habits of buffalo and wildebeest, which rendered the animals as black blobs against a green skyline, Dr. Sinclair was surprised when the wildebeest he was observing would suddenly just disappear, then reappear a little farther away, a few seconds later. After a few nights puzzling over this mysterious ability of the wildebeest to just "disappear," Dr Sinclair commandeered a powerful spotlight, which he switched on the moment the wildebeest did its disappearing act. Standing alongside the wildebeest was a zebra, which appeared invisible when seen through the goggles, its stripes a perfect camouflage for night, when predators, whose eyes may very well interpret light in the same way, are most likely to hunt.

Black Is Back -- The poaching onslaught of the '70s and '80s decimated black rhino numbers in Tanzania, and within these 2 decades, this stately mammal species, which had grazed the plains for 4 million years (2 million years before the earliest species of lion or elephant made an appearance), looked close to being declared nationally extinct. Serengeti authorities had given up hope until two female rhinos made their appearance in the Moru area (Central Serengeti) in the '90s. Much to the delight of the park wardens (and, no doubt, the rhino ladies), a Ngorongoro bull -- chased away by the dominant male in the crater and following traditional routes -- made his way west to Moru, where he chanced upon his small but ready-made harem. Since Rajabu's appearance (as the wardens have named him), four calves have been born, bringing the estimated rhino population throughout the greater ecosystem of the Serengeti (most of them residing in Kenya's Masai Mara) to around 100. However, many of these herds, including Rajabu's, are too small for a founder population. In an effort to conserve these, South Africa, which, along with Namibia has made the greatest strides in protecting the rhino, offered to donate 45 black rhinos, 18 of them females, to TANAPA. The project will be supplemented by the rhino repatriation program currently in place at Grumeti Private Game Reserve in the Western Corridor, where captive-bred East African black rhinos have been returned to their homeland and are currently adapting to their new environment before being released.

It's Not the Length, It's the Color -- In 2004, researchers from the University of Minnesota placed four life-size male toy lions in the Serengeti -- one with a long, dark mane; another with a short, dark mane; the third a long, pale mane; and the last a short, pale mane. Lionesses were initially fooled by the life-size toys -- long enough for the researchers to observe them flirting. They were most attracted to the lions with dark manes, regardless of length. When researchers then took samples of blood from real lions, they found that lions with dark manes had more testosterone and were better able to withstand being wounded. Therefore, a litter produced by a black-maned male stands a better chance of surviving.

Do Your Bit for Conservation: Shoot a Cheetah -- Tanzania is thought to hold 10% of the world's cheetahs -- along with wild dogs, Africa's most threatened carnivore. The Serengeti Cheetah Project is a 27-year-old study of individual cheetahs (all recognizable due to their unique spot patterns) run by the Tanzania Carnivore Conservation Project at the Tanzania Wildlife Institute. But they need all the help they can get, and tourists can be as helpful as park authorities. With their Cheetah Watch Campaign, anyone on safari in Tanzania can help ensure their survival by adding to the knowledge base. It's simple: If you spot a cheetah, no matter where, take a picture of it. (Whatever you do, don't disturb it/them in the process; not only are cheetahs shy, but they hunt during the day, and a vehicle can scare off its prey.) Make a note of where you are (your driver will be able to assist if you're not sure), as well as the date. When you get back home, e-mail your cheetah image(s) along with the "where and when" information, and the safari company/guide you were with, to; if you are okay with your photograph and information being posted on their website, say so. If the cheetah is identified, they will write and tell you a little about that cheetah's history.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.