Manatees

Perhaps a manatee isn't as "lovely" as this rose pictured above, but it is a very interesting and gentle giant.

MANATEE RESCUE EXHIBIT

On behalf of the Education Department at Sea World, let me welcome you to the Manatee Rescue Exhibit. My name is BERT. I am standing under the lights, in the center of the floor space. I will give you a few tidbits of information, but I am open to your questions at any time, but especially once I am done.

ü Safety: let me point out a few safety items first of all, for your personal well being. This exhibit hall is dim, so please be careful in walking around. In case you haven’t noticed, there is a ledge in front of the acrylic panels, and I have had a number of excited folks not see that ledge and run into it. The ledge is concrete, so you cannot possibly harm it, but it can do some damage to your shin. But, feel free to sit on the ledge if you are worn out from the warmth of the outside.

ü Now, first of all, let me introduce you to the 3 manatees here at Sea World, San Diego. They are Eddie, Vail, and Webster. Their names indicate that all 3 are males/boys.

Ø Eddie is actually the smallest of the 3, and he can be easily identified by that white scar, shaped like a starburst, very close to his tail. That is where he got hit by a boat, probably the propeller, and that is the reason that he was brought in to be “rescued.” He weighs over 1200 pounds, and is slightly longer than 9 feet. Eddie is over 8 years old.

Ø Vail is the medium sized of the 3, and he can be easily identified by having 2/3 of his tail missing. Closer inspection of that area will tell you that the boat prop probably hit him 3 times, judging from the 3 slash marks in the tail area. He weighs over 1400 pounds, and is well over 9 feet long. He is almost twice the age of Eddie at 15 years of age.

Ø The largest of the manatees is Webster, and he is almost the same age as Vail, but only about a year older at 16. Webster has no scars on his body, so he is the “clean” one. Actually, Webster was orphaned when his mother was killed by a boating accident, and so he was rescued and raised to his present size. He weighs in at 1800 pounds, and is nearly 11 feet long.

ü One of the first questions that we get at this exhibit is what and how much do these animals eat?

Ø The manatees here are fed mainly romaine lettuce, as it contains virtually all the nutrients found in their native diet of the grasses that grow in the rivers. If you are fortunate enough to be here when the diver places the food in the exhibit, you will notice that the diver puts the food at the bottom, usually wedged in under that long “log” in the center section of the exhibit. Manatees typically feed on the grasses by “feeling” them on the bottom, but they can also feed on the plant material floating at the top or even in the water column between the top and the bottom. As a treat, the manatees love apples, spinach, yams/sweet potatoes, and carrots.

Ø I know that some of you are thinking, “do you mean that these large animals only eat plant material?” Yep, but a lot of it. These 3 manatees are fed around 300 pounds of romaine lettuce daily, with each eating about a 100 pounds. So, if you want to get to be the size of a small manatee, you will have to eat a lot of salad in order to get there.

Ø You will notice that these manatees have what look like whiskers at the front of their snout/nose area. These are called the fancy name of vibrissae, which are like very sensitive long hairs. These serve the manatees for “feeling” the environment, and you might notice that the manatees will “explore” the exhibit by touching their snouts to the rocks.

Ø The manatees also use the pectoral flippers (the ones toward the front of the animal on the underside/ventral surface). These are handy in “collecting” the plant material toward their mouth.

Ø When the plant food is close to their mouths, the flexible lips are used in “grabbing and guiding” the food into their mouths. Both of these methods of gathering their food can be easily seen by watching them as they feed.

Now, just an aside. These manatees have been here since 1998, being brought here after being rescued by Sea World, Orlando. They are here for “long term rehabilitation,” and perhaps someday will be returned to their native Florida habitat in fresh water. Yep, the water in this exhibit is fresh water, and the manatees simply drink the water around them when they get thirsty. The exhibit itself is housed in acrylic panels in the front for easy viewing, and you need not concern yourself with that acrylic breaking or leaking. There are over 1,000,000 liters (280,000 gallons) of water, kept at around 76 degrees F. Manatees are very susceptible to cold conditions, suffering dramatically if the water temperature falls below 20 degrees C (68 degrees F.). Some of you might think that manatees, being so large, contain a layer of blubber, which you have heard the whales have, but that is not true. Yep, they have a lot of fat, but blubber is a special kind of fat that has a lot of connective tissue in its composition, all of which makes blubber an excellent insulating material. Since the manatees always live in warm waters, never dive deep enough to get to colder waters, they do not “need” blubber, and hence have not developed a layer of blubber, only a layer of fat. That layer of fat gives the manatee some buoyancy, which makes them able to either lie on the bottom comfortably (since the body is actually heavier than the water), or swim effortlessly around. The depth of the exhibit is 12 feet, and there is ample space for all 3 manatees to move around, feed, and play and explore.

ü Manatees are mammals, which means that they breathe air (need to get to the surface to get that air), give birth to live young, nourish their young with milk, are warm blooded, with an internal temperature much like ours, and possess hair at some point in their life cycle. Being mammals, they are different from the several species of fish that you see in the exhibit. These fish, all freshwater, are placed here to lend “ambience” to the exhibit, but the fish neither are fed on or feed on the manatees. The color posters that you see on the columns readily identify the different fish, so that you can make it your study to learn those fish, especially if you are an annual passport member and return to Sea World repeatedly. If I see you the next time you return, I will ask you which one is the “alligator gar,” or the “arapaima,” or the “red-tailed catfish.” This last fish is very, very easy to pick out, as are the other 2.

ü Also, since we are giving you pointers on “self study,” as you leave this central area, make an immediate left into a blind alcove/niche, where there are very informative and easily understood writeups on several aspects of a manatee’s life and anatomy and behavior.

One question that I will receive, especially if a manatee is “resting” on the bottom, is “…how long can it hold its breath?” 12 minutes is the answer, so if you see a manatee resting/sleeping on the bottom, and it has not been 12 minutes yet, be assured that there is nothing wrong with it: it is simply being a couch potato which is one of its favorite behavior patterns. Manatees are slow moving, swimming at speeds of 2-6 mph usually, but it can get up to around 15 mph for a short distance. But, you can see how agile and graceful they are, seeming to simply glide underwater. There is no need for speed in a manatee’s world, since its food are the various grasses, which do not “run away,” and there are not natural predators in its environment. Since their food is all in shallow waters, manatees do not dive deep, and their maximum depth of dives is probably less than 30 feet.

ü Reproduction: gestation period is about 12 months, and even though the Florida manatee breeds all year around, most of the calves seem to be born in the spring and early summer. A Florida manatee female produces a single calf about every 2-5 years. Twins are extremely rare. So, you can calculate that these animals are slow in replacing or building up a population, and with the number of manatees suffering from boat interactions, they have been placed on the Federal Endangered Species list, although the state of Florida is now considering legislation that takes them off that list.

ü In fact, one of the greatest cause of mortality/injury to manatees is its human interaction, meaning that they fun afoul of boats, fishing nets, and they used to be harvested for food.

ü A fairly interesting historical fact is that ancient sailors thought that manatees were the legendary “mermaids,” but these sailors must have had too much grog and been out to sea too long.

ü Manatees have excellent eyesight, so that they can probably spot a boat from quite some distance. But, they don’t envision the boat as a threat, and hence when the boat approaches too near, in its effort to dive away, it gets struck by the hull or the prop, either of which cause damage to the manatee.

ü Manatees probably live around 50-60 years.

ü The population of the Florida manatees is estimated to be well over 3000 (3276 in 2001 census), which is encouraging since in 1997, a census determined that there were only 2,229 remaining in the wild. The passages of legislation regulating boating activity and marine mammals disturbance make it encouraging that the Florida manatee will continue to persist in its natural environment.

v Your presence today and your continued patronage at Sea World insures that programs such as Manatee Rescue, stranded Seals and Sea Lions recovery, and shark population studies are carried on. Part of your admittance fees go toward the support of these programs, which would otherwise not be able to be carried on to the degree that they now exist.

Thank you very much for your visit to Sea World. For those of you who are annual Passport members, schedule a trip to Sea World at least monthly, get to know the different species of marine and fresh water animals that are featured here, and if you run out of animal species to identify, then start working on the many, many kinds of plants that abound in the park. The Horticultural Staff here at Sea World pride themselves in growing the lovely flowers and luxuriant foliage that you notice as you stroll through the part, going from one exhibit to the other.

Some other notes on Manatees:

They belong to the order SIRENIA, along with the dugong. All sirenians are found in warm tropical and subtropical waters. There are actually thought to be 3 species of manatees: the West Indian (the Florida and Antillean); West African (western coast of central west Africa); and Amazonian (the only one confined to fresh waters in the Amazon Basin, chiefly in Brazil). The dugong is more closely related to the now extinct Stellar Sea Cow, which became extinct in a mere 27 years after European fur traders discovered their population along the west coast of North America and hunted them for food. The Greek name for this order is derived from the “sirens” of Greek mythology. Sirens were sea nymphs who lured sailors/ships to their island with their mesmerizing songs, often causing those ships to collide with the shallow reefs.

The dugong is found in the Indian and western Pacific Oceans. The lone species left is the sole representative of the Dugongidae.

The 3 species of manatees are in the family TIRCHECHIDAE.

The West Indian manatees are composed of the 2 subspecies: the Florida and the Antillean. They are differentiated by their geographic distribution and cranial measurements; otherwise, they are very, very similar. The Florida subspecies is primarily found in peninsular Florida, but extends as far north as Rhode Island (rare) and have been rescued near Houston, Texas and Mississippi. The Antillean manatees are found in patches throughout the Caribbean, Mexico, and NE South America. The southern range extends through Central America and South America to Brazil.

The West Indian manatees, which include the Florida ones, inhabit rivers, bays, canals, estuaries, and coastal areas rich in seagrass and other vegetation. They can live in fresh, saline/salt, and brackish waters, moving freely between extremes at times. They may be found in any waterway that is deeper than 3.25 feet and connected to the coast. They prefer waters with temperatures above 70 degrees, rarely venturing into deep ocean waters.

Florida manatees move into warmer waters when the water temperature drops below 68 degrees. Historically, they have migrated south into warmer waters during the colder months of the year, congregating at the natural warm water springs. Today, power plant outfalls and other warm water discharges are important winter destinations for many manatees.

Populations of all species of manatees have declined over the past 100 years due to such causes as hunting for their meat, destruction of their habitats, boating, pollution, and low reproduction rates so that recovery of numbers is very slow.

Physical characteristics;

o Adult manatees average 10 feet in length, weighing about 800-1200 pounds. Females are generally larger than males. As I have described earlier, Webster, our largest manatee, a male, is now 11.5 feet long and weighs 1800 pounds.

o The manatee’s body is streamlined, full around the middle and narrowing to a paddle shaped tail. This type of body is said to be fusiform, which is a characteristic body shape for most of the marine mammals.

o The true color is gray, although it may appear to be brownish gray. Organisms such as algae, which may grow on the skin of slow moving individuals, alter the body color and make some manatees look more green or brown.

o The 2 small pectoral flippers (close to the head) are used for steering. These flexible flippers may also be used for bringing food to the manatee’s mouth and guding movement along a waterway ‘s bottom. They do have 3-4 fingernails at the tips of their flippers, like the toenails on an elephant’s feet. The flippers have 5 digits that are covered by a thick layer of skin. This bone structure is similar to that of toothed whales, seals, and sea lions. The alcove to your left as you leave this exhibit has an x-ray taken of the flipper that will clearly display the digits.

o The hind limbs are absent in manatees. Vestigial pelvic bones, which are not connected to the vertebral column, are found deep in the pelvic musculature, and represent the hind limbs found in other animals.

o There is no external ear flap, like those seen in sea lions. They are more like the true seals, with an auditory ear opening located just behind their eye.

o The nostrils are found at the end of the snout, as you can clearly observe. They are closed when the animal dives, and they have to be opened when the animal surfaces for a breath of air.

o They have a flexible upper lip, which helps guide vegetation into the mouth. Vibrissae/whiskers on the surface of the upper lip is attached to nerve endings and supplied with their own blood supply. They allow the manatee to “feel” their environment.

o They have 24-32 molars, located in the back of the mouth. The front molars in each row are continually worn down by the abrasive plants that the manatees eat; as the teeth wear down, new molars grow in the back of the mouth and gradually move forward. The replacement process continually provides new chewing surfaces as the teeth wear down, and continues through the manatee’s lifetime.

o In addition to the molars, manatees have horny, ridged pads at the front of the upper and lower jaws which aid in crushing plant materials.

o The tail is evenly rounded into a paddle shape and provides the major propulsion of the manatee by moving in an up and down motion.

o A manatee has hairs scattered sparsely over its body, with most of them being around the snout area.

Senses:

Hearing is not fully understood, other than that they are adapted for low frequency sounds. Hearing is an important sense for young manatees because mother and calf vocalizations are significant in keeping them together.

Manatees have well developed eyes, even though they appear to be small. In water, they can detect objects from tens of meters away. A nictitating membrane acts as an extra eyelid for protection.

Touch seems to be important for manatees. Body contact is common, especially between mother and calf. They have been observed even initiating contact with divers, and with inanimate objects such as ropes, buoys, logs, and rocks.

The manatee’s taste and smell characteristics have not been fully studied; they do have taste buds in the backs of their tongues and can most likely taste. They avoid certain plants, especially those that contain natural toxins.

Adaptations for living in an aquatic environment:

Ø They are quite agile and maneuver well under water, which you can readily observe. They have been clocked at speeds up to around 15 mph, but usually cruise at about 2-6 mph.

Ø They do not dive deep, probably less than 35 feet. This is so due to the fact that the vegetation that they feed on are all growing in the shallower depths.

Ø Their heart rate slows dramatically when diving, but they do not have some of the other adaptations that some of the other marine mammals have made for deep diving. Their muscles do not contain the higher concentrations of myoglobin for extra storage of oxygen. But, as is the case with most of the other marine mammals, they can renew about 90% of the air in their lungs in a single breath, as opposed to MAN’s 17%. While resting, manatees may remain submerged for as long as 20 minutes, although the average divers are for 2-3 minutes. More active and smaller manatees breathe more often.

Ø Manatees are nonaggressive, nonterritorial herbivores, spending most of their time feeding (6-8 hours daily), traveling, investigating objects, and socializing with other manatees.

Ø Manatees consume about 4-9% of their body weight in food daily. They feed primarily off the bottom, but they can also feed at the surface and anywhere in the water column. They have been observed cropping overhanging branches, consuming acorns, and may even haul themselves out of the water to eat bank vegetation including the leaves of mangrove trees.

Ø They require a source of fresh water for drinking. They have been seen drinking fresh water from hoses, sewage outfalls, culverts, and also congregating at river mouths. They must periodically have access to fresh water.

Reproduction:

Females may mature as young as 3 years of age, while males are usually mature by 9-10 years of age.

Cows do not form permanent bonds with bulls, and may mate with several bulls during the breeding season.

Manatees breed well in captivity, but it is not known how successful the offspring would be if released. Since space is limited at parks like Sea World, the emphasis is placed on the rehab and reintroduction of injured manatees instead of the establishment of a breeding program. All voluntary breeding programs are “on hold’ currently until the problems in the manatee’s natural environment become corrected.

Gestation is about 12 months, with most calves for the Florida manatee born during the spring and summer. A female produces a single calf once every 2-5 years. Twins are very rare. The calves are born in the water.

The calves are 4-5 feet long and weigh approximately 60-70 pounds.

The newborn calf is capable of swimming to the surface to get its first breath. They vocalize at or soon after birth, establishing the mother/calf bonding process.

Although the calves nurse for up to 2 years, they being nibbling on plants within a few weeks after birth. It is dependent on the mothers not only for nursing, but also for learning about feeding and resting areas, travel routes, and warm water refuges.

Longevity:

v They probably live for about 50-60 years.

v Although predation has not been documented, it is believed that sharks, alligators, or crocodiles may occasionally attack the manatees.

v They are susceptible to cold weather. It is not unusual for many to expire during extremely cold weather. During the exceptionally harsh winter of 2004, 50 manatees succumbed to the bad weather.

v As in any other animal population, manatees contract a variety of diseases and parasites. “RED TIDES” may also cause extreme distress in manatee populations, much like they do in seals/sea lion populations out here.

v Human impact, in the guise of watercraft accidents, flood gates and navigation locks, poaching and vandalism, accidental entanglement in fishing lines, crab lines, and those plastic wrappers used to transport 6 packs of cans, and habitat destruction, which is rapidly become the #1 human impact factor with southern Florida having a land development boom.

v All 4 species of sirenians are endangered or threatened, with the Florida manatee being the most endangered marine mammal in the United States.

Legal protection: All species of sirenians are protected to some extent by national/local acts in every country they inhabit. In the U.S., both Federal and state laws have been enacted to protect the Florida manatees. The Marine Mammal Protection Act of 1972 + the Endangered Species Act of 1973 make it illegal to capture, harm, or harass any marine mammal in U.S. waters.

Marine parks, like SEA World help the conservation effort by being authorized to rescue and rehabilitate ill, injured, or orphaned manatees. The first priority of this program is to return healthy manatees to their natural habitat. As I have already informed you, join the Sea World/Busch Gardens Conservation Fund, which sponsors lectures, seminars, legislative lobbying, and other programs that go toward the restoration of the Florida manatee population. In the last few years, the SWBG Fund has administered more than $2 million for 140 projects taking place in several countries for conservation. Find out more by visiting our customer relations counter, or go online to Seaworld.com or Seaworld.org.

Now, does anyone have any questions that we have not covered in this short talk, or that you missed due to your later arrival? Again, my name is BERT, and I represent the Education Department here at Sea World. I am located right under the lights, in the center part of the exhibit, dressed in my powder blue polo shirt, black shorts, and Yes, I am standing up as tall as I can! Have a great day here at Sea World.