User:Guy Fuchsia/Temp

3-36 ft (1 to 12 m) 68-107 F (20-36C) turbid and salt contant changes seasonally

General Sirenian
 * docile, slow moving (SeaLife 413)
 * paddles move at the elbow; upper arm enclosed within the flank (SeaLife 413)
 * tail is flattened for propulsion; lobes supported only by a central row of caudal vertebrae (SeaLife 413)
 * nostrils open at top of muzzle as a pair of circular nasal openings, and are closed by anteriorly hinged valves (SeaLife 413)
 * teats are in "armpits" just behind paddles of the female (similar to elephants) (SeaLife 413)
 * head is flat-faced, heavy-jowled, densely bristled (SeaLife 414)
 * two enlarged lobes on the upper lip hang down (SeaLife 414)
 * prominent bristly chin (SeaLife 414)
 * ear canal opens at the surface behind the eye (SeaLife 414)
 * eyes are small within welldefined eyelids and are protected by heavy tear secreton (SeaLife 414)
 * name derived from mythical Greek nymphs (SeaLife 414)
 * ungulate features in teeth, skull, skeleton and soft tissues (SeaLife 414)
 * distantly related to elephants (SeaLIfe 414)
 * distribution probably limited by their sensitivity to low water temperature (SeaLife 415)
 * limited ability to raise metabolic rate in cold water (SeaLife 415)
 * swimming is produced by the tail, which moves up and down with powerful strokes (SeaLife 415)
 * when changing direction, the tail acts as a horizontal rudder by twisting on its axis while stroking is stopped (SeaLife 415)
 * paddles are used for guiding turns and decelerating; in fast swimming they are raised and held against the sides. (SeaLife 415)
 * slow-swimming when undisturbed (SeaLife 415)
 * dive with their lungs full of air (SeaLife 415)
 * bones are dense and heavy due to loss of marrow in ribs and long bones choked with hard bony tissue (SeaLife 417) (Pachyostosis)
 * among the densest animal bones ^
 * ribs may have a ballast-like action, steadying sirenians in water and partly counteracting high center of gravity from lungs (SeaLife 417)
 * eat variety of aquatic plants (SeaLife 417)
 * use their paddles to assist with manipulating food, swishing it in reach of their mouths (SeaLife 417)
 * bristles around snout help to deal with slippery strands guided by muscular lips into the mouth/ the lips of the left and right sides can move independently (SeaLife 417)
 * bristles have comparable function to cropping tongue and lips of cattle (SeaLife 417)
 * horny pad at the tip of upper and lower jaws helps to grip and break off aquatic vegetation which is passed back into the mouth (SeaLife 418)
 * long digestic tract characteristic of herbivorous mammals. (SeaLife 418)
 * stomach is multi-chambered but small in comparison to cattle; large intestine acts as fermentation chamber (SeaLife 418)
 * this is similar to hind-gut ruminants (horses, elephant) (SeaLife 418)
 * LI harbors a rich microflora that breaks down tough cellulose (plant cell wall) component in digesta (SeaLife 418)
 * use of aggregations not entirely known (SeaLife 419)
 * chirp, squeek sounds of low freq (<20kHz) (SeaLife 419) unknown use?
 * low reproductive rate (SeaLIfe 419)
 * hunting probably had little effect on pop. until introduction of modern techniques and equipment (SeaLife 420)
 * netted trapped harpooned and dynamited in many parts of their range for meat, skin and oil. (SeaLife 420)
 * shallow riverine and tropical coastal habitats of sea cows are suitable as prime development sites and the future commercialisation of sea cow habitat will place furhter pressure on their pops (SeaLife 420)
 * until more is known the intro of effective measures is difficult (SeaLife 420)
 * aerial survey is the techniq of choice for locating widely distributed sea cows because it can cover large areas in remote regins (SeaLife 420) BUT NOT AVAILABLE IN ALL RELEVANT COUNTRIES
 * sea cows living in turbid coastal waters or in areas with overhanging vegetation are difficult to spot from aircraft (SeaLife 420)

Dugong
 * pointed forelimbs (instead of rounded), nails absent (SeaLife 414)
 * skin unpleated, surface relatively smooth (SeaLife 414)
 * hairs on body short and rigid (SeaLife 414)
 * ear openings large and easily visible (SeaLife 414)
 * nostrils at muzzle tip (SeaLife 414)
 * tusk-like incisors (up to 18cm) (SeaLife 414)
 * animal of tropic seas with a wide but discontinuous Indo-Pacific distrib from the head of the Gulf of Suez (32 E) to the New Hebrides (170 E) (SeaLife 415)
 * thin blubber and lacks heat exchangers in the skin (SeaLife 415)
 * paddles used for sculling at low speed or for pivoting the body above the bottom during resting or feeding (SeaLife 415)
 * burst speeds of 10-12 knots (short distances) (SeaLife 415)
 * Can dive for about ten minutes, half as much as manatee (SeaLife 415)
 * ribs are shorter and thinner (SeaLife 417)
 * spine is thinner, shoulder blades smaller (SeaLife 417)
 * probably evolved to become less dependent on static buoyancy mechanisms (SeaLife 417)
 * diet includes Enhalus, Amphibolis, Halophila, Halodule, Cymodocea, Tahalassia, Thalassodendron, Syringodium, Zosetra. (SeaLife 417)
 * leave distinct feeding trails visible at low tide when feeding on small delicate sea grasses (eg halodule/halophilia) because they eat roots rhizomes and leafs. (SeaLife 417)
 * with tall growing seagrasses only the leaves are cropped (SeaLife 417)
 * In red sea, they use paddles to dig sea grass from the sediment (SeaLife 417)
 * large intestine 25m long, twice as long as small (SeaLife 418)
 * tapetum lacking in dugong (SeaLife 418) LITTLE KNOWN ABOUT VISION
 * reaches puberty for both sexes at 10 (SeaLife 419)
 * one calf at a time with long rest periods, calves suckle for at least 18 months and born after 12 months (SeALife 419)
 * with life span 70, avg calving interval 5, female dugong cannot expect to produce more than 12 young. (SeaLife 419)
 * sustainable level of capture of female dugongs is as low as 2% per year in all females in a population (SeaLife 419)
 * tusks erupt at the male gum at about 12-15 years old, coinciding with sexual maturity. (SeaLife 419)
 * tusk-tip worn to a chisel-like edge, the beveled surface lying on the outer or lip-facing side (SeaLIfe 419)
 * use remains speculative (SeaLife 419)
 * paired scars found on dugongs backs could have been produced by rivals tusks although there is evidence that males fight for access to breeding females (SeaLife 419)
 * tusks may be needed to grip the smooth back of the female during the process of turning the female on her back in the water prior to making, however tusks also erupt in old females (SeaLife 419)
 * little information on birth although it suggests that female breaches or drags herself onto a sandbar to give birth (SeaLife 420)
 * one observation of a head-first delivery (SeaLife 420)
 * if true then female dugong retains a residual attachment to the land in the reproductive cycle (SeaLife 420)
 * calves are about 1-1.2m long in the dugong at birth (SeaLife 420)
 * north coast of australia has a pop of up to 70k dugongs and a year round pop of 17k in the gulf of carpenteria (SeaLife 420)
 * protected by law in australia (SeaLife 420)
 * no longer occurs in the laccadive maldive chagos nicobar barren narcondam cocos (keeling) christmas and lesser synda islands. (SeaLife 420)
 * relict pop in palau island where it is under threat of extirpation due to illegal poaching (SeaLife 420)

Dugong?
 * makes abrupt movements to the left or right using paddles
 * ascend/descend effortlessly through the water column (probably not)
 * food takes week to pass through gut / 100kg a day in a large manatee
 * mothers/calves interact vocally?
 * small eyes but see well underwater
 * shiny reflective layer behind the eye (tapetum lucidum) characteristic of animals that use vision at night
 * manatees retain sense of smell and olfactory nerves are prominent in base of brain, taste buds at back of tongue

BIBLIO Harrison... 1980 Marine Mammals Marsh, H....1979 The Dugong reynolds....Manatees and Dugongs