Presentation on theme: "Proboscidea Proboscidea (animals with trunks/proboscis)"— Presentation transcript:
Proboscidea Proboscidea (animals with trunks/proboscis)
It is believed that 50-60 mya, mammals approximately the size of current day pigs, were the roots from which the proboscideans evolved. Based on both morphological and biochemical evidence, it is agreed that the manatees, dugongs, and hyraxes are the closest living relatives of the today's elephants.hyraxes History
History This mammal order belonging to the Tethytherians evolved in Africa during the Eocene, about 60 mya Includes over 300 species (some taxonomist count 129) and is the highway for the evolution of the elephants The oldest proboscidean is Anthracobune, from early or early- middle Eocene (˜50 mya), was found in Africa and Asia, in shore or semi-aquatus shallow environments, but Proboscideans inhabited a wide range (North America, Asia, Europe, and Africa)
Evolution About 50-60 mya, the ancestors of the modern elephant occupied a variety of extreme environments; from tropical rainforests to deserts in both low and high altitudes. With the exception of Australia and Antarctica, the proboscideans have over time inhabited every single continent on Earth. Why did all but two species become extinct? Inability of the order to evolve to environmental change fast enough
Evolution The mammoth, Asian elephant, and African elephant all originated in Africa. It was only the African elephant that ended up staying and evolving to the animal we know today solely in Africa. The mammoth became extinct as recently as 5 kya; fossil records indicate that hunting by Man was a factor in eliminating the mammoth, as well as global warming.
Living Species African elephants (Loxodonta) live in central Africa, from Democratic Republic of the Congo to Mauritania, and are divided into two subspecies (savannah and forest). Asian elephants (Elephas maximus) inhabit India, Sri Lanka, Myanmar, Indonesia, Thailand, Cambodia, Vietnam, Laos, Malaysia, Nepal, Bangladesh, and southern China, and is divided into four subspecies (Sri Lankan, Indian, Sumatran and Borneo).
Physical Characteristics Height: 5-14 ft at shoulders (males); females of all subspecies are smaller than males. Length: Up to 30 ft trunk to tail. Weight: 6,000-15,000 lbs (males). Lifespan Up to 70 years. Long, muscular trunk that functions almost as a fifth limb, and males have a pair of huge tusks derived from upper incisors. Their cheek teeth are uniquely adapted to their highly abrasive diet.
Habitat Live in tropical and subtropical regions Minimal Needs Variety of habitats: Savannas (grassland and woodland) Rainforests Mountains Semi-deserts Deciduous forests Within a day's walking distance of water
Diet Staples: Grasses, leaves, bamboo, bark, roots. Elephants are also known to eat crops like banana and sugarcane which are grown by farmers. Adult elephants eat 300-400 lbs of food per day. They are capable of pushing down large trees in order to get at their foliage and bark. (The skeleton of elephants is adapted to bear massive weight). Foraging herds can be very destructive of cropland or forest.
Reproduction Mating Season: Mostly during the rainy season Gestation: 22 months Litter size: 1 calf (twins rare) Calves weigh between 200-250lbs at birth At birth, a calf's trunk has no muscle tone, therefore it will suckle through its mouth. It takes several months for a calf to gain full control of its trunk Sexual maturity is reached between 12-14 yrs Cows typically give birth to 1 calf every 5 years
Behavior Typical life span is 60-70yrs Complex social structure is matriarchal and family is at the core (3-25 members), individuals greet one another by making sounds and touching each other with their trunks They communicate by means of a variety of sounds, some produced vocally and others by tapping or stamping on the ground Extremely intelligent animals and have memories that span many years They also display signs of grief, joy, anger and play
Climate Change & Other Threats Habitat loss Many climate change projections indicate that key portions of elephants’ habitat will become significantly hotter and drier, resulting in poorer foraging conditions and threatening calf survival Increasing conflict with human populations taking over more and more elephant habitat and poaching for ivory are additional threats At the turn of the 20th century, there were a few million African elephants and about 100,000 Asian elephants. Today, there are an estimated 450,000 - 700,000 African elephants and between 35,000 - 40,000 wild Asian elephants.
Case Study: African Elephants Respond to Distant Playbacks of Low Frequency Conspecific Calls (Langbauer,1991) The purpose of this study was to estimate the distance over which African elephants can perceive the low-frequency calls of conspecifics 58 playback experiments with free-ranging African elephants in Etosha National Park, to estimate the distance over which some of their low-frequency calls are audible to other elephants Broadcast pre-recorded elephant calls to elephants that were 1.2 and 2.0 km from the loudspeaker, using 5 different stimuli
Case Study: African Elephants Respond to Distant Playbacks of Low Frequency Conspecific Calls (Langbauer,1991) At distances of more than a few meters, many of the low-frequency calls are entirely inaudible to the human ear These calls appear well suited for transmission over long distances since low-frequency sound propagates more effectively than sound at higher frequencies Long-distance acoustic communication would help explain some enigmatic aspects of elephant social behavior (coordinated movements of cow- calf groups)
Case Study: African Elephants Respond to Distant Playbacks of Low Frequency Conspecific Calls (Langbauer,1991) For each experiment, the subjects consisted of all elephants present at the waterhole when the playback was broadcast Classified as being either a 'male' trial or a 'cow- calf group' trial A full response consisted of the elephant vocalizing, lifting and spreading its ears, remaining motionless in this position, moving the head from side to side and, in the case of males responding to female estrous calls, orienting to and finally walking 1 km or more towards the loudspeaker
Case Study: African Elephants Respond to Distant Playbacks of Low Frequency Conspecific Calls (Langbauer,1991) All the calls used as stimuli elicited responses from the subject elephants Animals in cow-calf groups tended to give vocal responses more than animals in all-male groups Male responses tended to persist longer and to involve movement over longer distances than did those of cow-calf groups Results support the hypothesis that the low- frequency calls of elephants function in communication among elephants over distances of several kilometers