EEBIOL 151 Creatures of the rivers
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- South American Rivers
- Amazon, Orinoco
- African Rivers
- Congo (Zaire), Niger, Nile
- Southern Asia Rivers
- Mekong, Ganges
- Amazon region
- - was once a huge inland sea/lake - was caught between 2 higher, ancient geologic structures (Guyana highlands and Brazilian highlands) - River outlet was to the west before the Andes formed.
- Amazon drainage
- - not longest, but volume flowing is huge - twice per month major tides by force of moon (pororoca) - has been 80 m deep in the past - first fully explored by Francisco de Orellana
- accounts of Amazon explorers
- - First discoverer was Amerigo Vespucci - Traveled 150 miles up river - convinced Vespucci that the new land was not an island, that it must be a continent, so it couldn't be the West Indies - originally called Pinzon Rio Maranon
- Lungfishes
- - only 3 living species, all occur in tropical regions - Amazon lungfish is closely related to the Congo/African one (remember that these two continents were once joined) - Queensland lungfish was derived from a once marine family of lungfishes, and adapted to fresh water. Other marine versions died out.
- Fishes - Amazon and Africa
- - most endemic freshwater fish spp. of Amazon are ancient and share ancestry with African versions. - characins (tetras, other aquarium fish) - catfishes - cichlids - knifefishes of S. America evolved from Amazonian characins - remnants of Gondwanaland connection more than 110 MYA
- Cichlids of east african lakes
- These are the fish that have radiated in the east african lakes. The ones they use as an example of adaptive radiation.
- Big Animals of the Amazon River
- - Giant catfish - black caiman - anaconda - amazonian manatee - amazonian sideneck turtle river dolphins (2 spp, pink and grey) - 6+ m sawfish in lower river
- Amazon Sideneck River turtle
- - also called arrau (tartaruga) - is a huge herbivore that can grow to 70 kg (150 lbs) and live 30 years, and can get a carapace (shell) up to 1 m long - females lay eggs resembling ping pong balls in sandbars during dry season; they choose certain sandbars that aren't eroded by storms or washed away by rain. - eggs incubate 2 months in warm sand - hatchlings scramble to get to water, high predation rate. - named for the s-shaped swan neck they have
- Arapaima (amazon) and Dragon fish/arowana (s. asia)
- - amazonian species up to 3 m, 250 lbs. - mother cares for young for 4 months with milky fluid from pores in head - amazonian arowana are excellent jumpers, sometimes called macaco d'aqua (water monkey) - can jump out of water and get stuff from low hanging branches - Asian arowana hatch young in mouth of male (parental investment)
- River dolphins
- - freshwater species, eat cichlids and characins. - in the Amazon, there's a pink species and a gray species - superstition: lure women into water to have intercourse with them
- freshwater manatees and Dugong
- - eat aquatic plants - amazon manatee - indo-pacific dugong - west african manatee - eat hyacinth, water lilies, water lettuce, etc. - can submerge for 3 minutes and have few natural predators except humans. - manatees are freshwater, dugong is sea water species, occurs along coastal forests
- Aquatic plants
- - abundant in quiet, warm waters - 3 general life strategies: floating plants/leaves with no anchoring, submerged, feather aquatics, or plants that only let leaves stick out of water. - life is easy, with all the water and nutrients they need. - food for mammilian herbivores like manatees, capybaras, and hippos.
- Giant Water lily/Victoria water lily
- - a giant amazonian water lily greater than 1 meter across - have pictures of babies in these, while they are still floating. - live in shallow backwaters
- Anacondas
- - a python and constrictor, so it squeezes prey - semi aquatic; will usually only come onto land to slither between pools in the dry season - lays eggs - rumored to prey on human children - females can grow 10+ m long, while males are only 1/5 this size. - may exceed 250 kg - females are largest snakes in the world
- 7 deadly plagues of Rivers Amazon
- - anaconda - piranhas - piraiba candirus electric knifefish (saporo) - stingrays - black caiman
- Piranhas
- - have an exaggerated reputation - razor sharp teeth, powerful jaws, give coin sized bites - especially dangerous when trapped in shallow water - attracted by commotion, blood, red coloration
- flesh-eating catfishes
- - parasites of larger fishes in Amazon. chew holes in them and suck blood. - greatly feared because a school can skeletonize a human in less time than piranhas - attracted to smell of urine
- Electric knifefishes (electric eels) of S. America
- - described by Alexander von Humboldt - difficult to capture, he exhausted them with animals - use electricity to hunt, by creating a field around themselves and sensing disturbances in it - can emit shock of up to 800 volts - electric organ in tail generates the signal, and electric receptor pores are found in the head. - can swim backwards
- Fishes and seed dispersal
- Certain fishes eat fruits and thereby disperse seeds of plants in S. America, especially in Varzea where it is flooded for a few months of the year.
- Perils of African Waterways
- - hippos - crocodiles
- Hippos
- - huge herbivores, easily angered, very territorial - large body size eliminates all natural predators - can hold breath up to 6 minutes. - feet have nails, and not hooves - stay in shallow water and walk along the bottom of the riverbed. Can't swim. - close ears and nose when submerged, but communicate through clicks that sound like dolphins. this is because they are closely related to dolphins.
- Crocodilians
- - 22 species - are sit and wait hunters - eyes supposedly can see color - advanced brain - valves over ears, nostrils, and membrane over eye to protect these senses. - crocodiles, alligators, gavials - sex of offspring is determined by temperature. Lower temperatures make females, higher temperatures make males. - females guard nests and then care for young until they can forage on their own - only one species can deal with saltwater, and it has special adaptions such as salt glands on the tongue that excrete drops of concentrated salt solution
- Australia aquatic animals - monotreme
- - duck billed platypus, lays eggs - has a venom gland in thigh and a spur on the back foot by which this can be delivered - bottom feeder with a sensitive "bill"
- anurans (frogs)
- - saltatory movement (jumping) - see mostly sharp edges/movement, so they can't see well unless something moves in front of them. If it is bigger than them, they leave it alone, smaller and it is potential prey. - projectile tongue - tongue is attached to the front of the mouth. Jaw drops open, tongue flops out, and stretches, and catches prey on a stick tip before being yanked back in. - fertilized eggs are in water, protected from dessication but vulnerable to aquatic predators - have complete metamorphosis - about half of all frogs in the world are native to Neotropics. - pools can have up to 10 breeding spp at a time, with separation by mating calls.
- Anurans - where they place eggs
- - can place in ponds, but have high predation rates and competition with other tadpoles. - can also use tank epiphytes, or tree hollows - foam nest construction (where adults beat the jelly stuff surrounding the eggs into a foam, which then solidifies and provides protection and food for young) - highly humid leaf nest - several tree frogs have internal fertilization