4. 수생조류
1) 외부형태 및 골격계
(1) 수생조류(waterfowls)는 펭귄류(pehguins ; Speniscidae), 아비류(loons ; Gaviidae), 신천옹류(albatrosses ;
Diomedeidae), 바다제비류(petrels ; Procellariidae), 가마 우지류 (cormorants ; Phalacrocoracidae), 사다새류
(pelicans ; Pelecanidae), 갈매기류(gulls ; Laridae), 그리 고 오리, 백조(swan), 기러기(wild goose) 등이 속하는 오리 류(ducks ; Anatidae) 등이 있다.
External anatomy (topography) of a typical bird: 1 Beak, 2 Head, 3 Iris, 4 Pupil, 5 Mantle, 6 Lesser coverts, 7 Scapulars, 8 Coverts, 9 Tertials, 10 Rump, 11 Primaries, 12 Vent, 13 Thigh, 14 Tibio-tarsal articulation, 15 Tarsus, 16 Feet, 17 Tibia, 18 Belly, 19 Flanks, 20 Breast, 21 Throat, 22 Wattle
(2) 대부분 공중을 날 수 있도록 잘 적응되어 있으며, 머리, 목, 몸 통, 꼬리의 4부분으로 구분된다.
(3) 몸은 깃털로 덮여있고, 앞다리는 일반적으로 날 개로 변하여 나는데 사용하나, 퇴화하여 날지 못 하거나 잠수에 사용하는 것 등이 있다.
(4) 뒷다리는 파충류와 같이 비늘로 덮여 있으며, 탈리한다. 펭귄의 경우 뒷다리가 몸 뒤쪽에 있어 걸을 때 직립하는 모
양(penguin waddling)을 한다.
(5) 펭귄이나 오리와 같이 발가락은 헤엄을 치든가 잠수하면서 먹이를 잡는데 편리 하게 물갈퀴(webbing)가 있거나, 논병 아리(little grebe)와 같이 갈라진 노처 럼 변형된 것도 있다.
(6) 날기에 적합하게 조류의 골격은 속이 비어 있는 가볍고 강한 뼈로 구성되어 있어 몸무게를 최소화한다.
(7) 턱의 기부에 경첩을 이루는 관절이 있어 위턱과 아래턱을 모 두 움직인다.
(8) 각 갈비뼈는 편평하고 뒤로 튀어
나온 구상돌기(uncinate processes of ribs) 가 발달되어 있다.
(9) 대부분의 조류는 앞 3가락 뒤 1가 락의 4개의 발가락을 가지고 있어, 나뭇가지를 붙잡는데(perching) 적합하다.
hollow with criss-crossing struts or trusses
(10) 포 유 류 보 다 더 많 은 경 추 (cervical vertebrae) 를 가 지 고 있 어 마 음 대 로 목 을 구 부 릴 수 있어서, 먹 이 를 찾 거 나 움 직 이 는 데 편 리 하다.
wishbone=
(창사골)
The furcula is commonly referred to as a wishbone or merrythought because of the tradition that when two people hold the two sides of the bone and pull it apart, the one who gets the larger part will have a wish granted. Because this is commonly a Thanksgiving tradition, this bone is also called the Thanksgiving bone.
Archaeopteryx lithographica, is the earliest bird in the fossil record, coming from the Late Jurassic lithographic limestone, Germany. The first specimen was found in 1891, almost
coincident with Darwin's publication of Origin of Species two years later, and ten more have since been found.
Archaeopteryx was about the size of a crow with short, broad wings and a long tail. While its feathers were similar to those of living birds, it had jaws lined with sharp teeth, three fingers ending in curving claws, and a long bony tail, in stark contrast to modern birds.
Archaeopteryx's many features of dinosaurs such as the jaws with teeth, tiny forelimbs with three claws, a long tail and a head covered with scales while body, wings and tail were covered with feathers as in a bird provides strong evidence of the dinosaur ancestry of birds, and, more generally, of the validity of the Theory of Evolution.
Archaeopteryx (시조새)
2) 피부
(1) 피부에는 분비선이 거의 없고, 꼬리 융기부에 있는 우지선 (기름샘 ; uropygial gland)의 기름(preen oil)으로 깃털 을 방수한다.
(2) 깃털(contour feather)은 섬유성 단백질인 케라틴으로 구성 되어 있어 능률적인 비행이 가능하며, 기부에
는 솜털(pinfeather)이 있어 단열작용 (insulation)을 한다.
(3) 피부의 평활근에는 모낭 (hair follicle)에 연결된 작은 날개근육(skin
muscle)이 있어 깃털을 서게 한다.
(4) 일반적으로 번 식기가 지나면 털갈이
(molting)를 한다.
Preening of birds
The uropygial gland, or, more informally, the preen gland is a gland found in the large majority of birds that secretes an oil (preen oil) that birds use for preening. The chief compounds of preen oil are diester waxes called uropygiols.
The gland is found near the base of the tail and is shaped into two symmetric parts. The oil of each part of the gland is secreted through the surface of the skin through a grease nipple-like nub. A bird will typically transfer this oil to its feathers by rubbing its head against the oil and then around the rest of the body. Tailward areas are usually preened utilizing the beak. Not all birds have a uropygial gland.
Exceptions include the emu, ostrich, and bustards. These typically find other means to stay clean and dry, such as taking a dust bath. The uropygial gland is strongly developed in many waterbirds, such as ducks for
waterproofing. In vitro study, Antiparasitic effect that the preen oils are effective against lice was suggested.
Feathers in birds
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds. They are considered the most complex integumentary structures found in vertebrates. They are among the characteristics that distinguish the extant Aves from other living groups. Although feathers cover most parts of the body of birds, they arise only from certain well-defined tracts on the skin. They aid in flight, thermal insulation, waterproofing and coloration that helps in communication and protection.
Feathers are among the most complex integumentary appendages
found in vertebrates and are formed in tiny follicles in the epidermis, or outer skin layer, that produce keratin proteins. The β-keratins in feathers, beaks and claws — and the claws, scales and shells of reptiles
— are composed of protein strands hydrogen-bonded into β-pleated sheets, which are then further twisted and crosslinked by disulfide bridges into structures even tougher than the α-keratins of mammalian hair, horns and hoof.
Parts of a contour feather:
1. Vane 2. Rachis 3. Barb
4. Afterfeather
5. Hollow shaft, Calamus
3) 소화계
(1) 입이 부리(beak)로 되어 있으며, 입술과 이가 없다. 혀에는 이빨 같은 것(papilla)이 있어 먹이를 식도로 밀어 넣게 되 어 있다.
(2) 부리는 위아래 양 턱뼈의 돌출한 케라틴층으로 덮여 있으며, 부리 끝이나 혀에 Herbst corpuscle
이 있어 땅속에 있는 먹이를 검색하는 역할을 한다.
Feeding adaptations in beaks
Sharp teeth like structures in the bird's mouth called papillae help birds hold and move food around.
Most birds are unable to swallow by the "sucking" or "pumping" action of peristalsis in their esophagus (as humans do), and drink by repeatedly raising their heads after filling their mouths to allow the liquid to flow by gravity, a method usually described as "sipping" or "tipping up".
Herbst corpuscles in birds
The Corpuscles of Herbst or Herbst corpuscles are a nerve-ending similar to the Pacinian corpuscle, in the mucous membrane of the tongue, in pits on the beak and in other parts of the bodies of birds. It differs from the Pacinian corpuscle (a mechanoreceptor is a sensory receptor that responds to
mechanical pressure or distortion) in being smaller, in its capsules being more closely approximated, and in that the axis-cylinder in the central clear space is coated with a continuous row of nuclei. In many wading birds, a large number of Herbst corpuscles are found embedded in pits on the mandibles that are believed to enable birds to sense prey hidden
under wet sand or soil using minute pressure differences in the water.
Sensory pits in the upper and lower bill of a female Western Sandpiper (A, lower bill and B, upper bill), male Western Sandpiper (C, lower bill), female Dunlin (D, lower bill), male Dunlin (E, upper bill), and male Least Sandpiper (F, upper bill). Herbst corpuscles are found in high densities in these sensory pits (Nebel et al. 2005).
Beak in birds
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, probing for food, courtship and feeding young.
Beaks vary significantly in size and shape from species to species. The beak is composed of an upper jaw, called the maxilla, and a lower jaw, called the mandible. The jaw is made of bone, typically hollow or porous to conserve weight for flying. The outside surface of the beak is covered by a thin horny sheath of keratin called the rhamphotheca.
Between the hard outer layer and the bone is a vascular layer containing blood vessels and nerve endings.
The beak has two holes called nares (nostrils) which connect to the hollow inner beak and thence to the respiratory system. The nares are usually at the base of the beak, near the dorsal surface.
(3) 식도는 팽창이 잘되며 일시에 많은 먹이를 저장할 수 있 는 근육성의 소낭(모 이주머니 ; crop)이 있어 먹이를 부드럽 게 하고 먹이의 흐름 을 조절한다.
(4) 위는 위액이 분
비되는 전위(proventriculus)와 자갈이나 돌이 들어 있어 포유류의 이빨 과 같이 음식물을 분 쇄시키는 역할을 하 는 두꺼운 근육으로 쌓여 있는 근위(모래 주머니 ; gizzard)로 되어 있다.
Digestive system in birds
Many birds possess a muscular pouch along the oesophagus called a crop. The crop functions to both soften food and regulate its flow through the system by storing it temporarily. The size and shape of the crop is quite variable among the birds. Members of the order Columbiformes, such as pigeons, produce nutritious crop milk which is fed to their young by regurgitation. Birds possess a ventriculus, or gizzard, composed of four muscular bands that rotate and crush food by shifting the food from one area to the next within the gizzard. The gizzard of some species contains small pieces of grit or stone swallowed by the bird to aid in the grinding process of digestion, serving the function of mammalian or reptilian teeth. The use of
gizzard stones is a similarity between birds and dinosaurs, which left gizzard stones called gastroliths as trace fossils.
Cormorant fishing (Ukai)
Cormorant fishing is a traditional fishing method in which fishermen use trained cormorants to fish in rivers.
Historically, cormorant fishing has taken place in Japan and China, as well as other places throughout the world. To control the birds, the fishermen tie a snare near the base of the bird's throat. This prevents the birds from swallowing larger fish, which are held in their throat(crop), but the birds can swallow smaller fish. When a cormorant has caught a fish in its throat, the fisherman brings the bird back to the boat and has the bird spit the fish( ayu=sweetfish) up. Though cormorant fishing once was a successful industry, its primary use today is to serve the tourism industry. The types of cormorants used differ based on the location. In Gifu, Japan, the Japanese Cormorant (P. capillatus) is used; Chinese fishermen often employ Great Cormorants (P. carbo).
(5) 조류는 포유류와 같이 식도의 연동운동(peristalsis)에 의 해 물을 삼키지 못하므로, 물을 입에 채운 후 중력에 의해 물이 아래로 흘러 내려가도록 머리를 들어줘야 한다
(sipping).
(6) 조섬유의 발효와 소화작용을 하는 맹장을 2개 가진다.
(7) 배뇨와 배변, 산란을 함께 하는 배설강 (cloaca)을 가진다.
4) 순환 및 호흡계
(1) 허파호흡을 하며, 여러 쌍의 공기주머니(기낭 ; air sac)가 폐 에 연결되어 있고, 뼈 속까지 뻗어 있다. 기낭은 비행 중 근육에서 생성된 열을 공기를 통해 발산하는 체온조절 기능과 덥혀진 공기 에 의해 부력을 조절한다.
(2) 허파에는 포유류에서와 같이 폐포가 없는 대신에 기관지로부 터 연결된 수많은 가는 빗살모양의 측기관지(parabronchi)를 통 해 공기가 기포(atria=air vesicle)로 들어가 기포 안의 모세혈관 에서 가스교환이 일어난다.
(3) 횡격막이 없으며, 체강이 근육의 수축에 의해 풀무(bellows) 와 같이 작용하여 숨을 내쉴 수 있다.
(4) 조류는 포유류에 비해 상대적으로 긴 기관(trachea)을 가지 며, 소리를 내는 기관인 울음관(syrinx)이 기관 하단부에 있는데 공기가 유입되면 울음관의 진동에 의하여 소리를 낸 다.
Birds lungs obtain fresh air during both exhalation and inhalation
Birds ventilate their lungs by means of air sacs, structures unique to birds. These sacs do not play a direct role in gas exchange, but to store air and act like bellows, allowing the lungs to maintain a fixed volume with fresh air constantly flowing through them.
Avian lungs do not have alveoli, as mammalian lungs do, but instead contain millions of tiny passages known as parabronchi, connected at either ends by the dorsobronchi and ventrobronchi. Air flows through the honeycombed walls of the parabronchi into air vesicles, called atria, which project radially from the parabronchi. These atria give rise to air capillaries, where oxygen and carbon dioxide are traded with cross- flowing blood capillaries by diffusion.
Birds also lack a diaphragm. The entire body cavity acts as a bellows to move air through the lungs. The active phase of respiration in birds is exhalation, requiring muscular contraction.
Air always flows from right (posterior) to left (anterior) through a bird's lungs during both inhalation and exhalation. Air enters the bird via the trachea. Half of the inhaled air enters the posterior air sacs, the other half passes through the lungs and into the anterior air sacs. The sacs contract during exhalation. Air from the
anterior air sacs empties directly into the trachea and out the bird's mouth or nares. The posterior air sacs empty their air into the lungs. Air passing through the lungs as the bird exhales is expelled via the trachea. Because fresh air flows through the lungs in only one direction, there is no mixing of oxygen-rich air and oxygen- poor, carbon dioxide-rich, air as in mammalian lungs.
The syrinx is the sound-producing vocal organ of birds, located at the base of a bird's
trachea. As with the mammalian larynx, sound is produced by the vibration of air flowing through the organ. The syrinx enables some species of birds to produce
extremely complex vocalizations, even mimicking human speech(i.e. parrot). In some songbirds, the syrinx can produce more than one sound at a time.
(5) 항온성으로 체온이 약 40℃이며, 땀샘이 없어 가쁜 숨을 몰 아 쉬어 열을 방출한다. 또는 혈액을 깃털이 없는 뒷다리로 보내 체온을 조절하는 것도 있다.
(6) 심장은 2심방 2심실로, 체순환과 폐순환을 한다.
(7) 혈액은 포유류와 달리 핵이 있는 적혈구와 백혈구, 그리고
혈소판으로 되어 있다.
들이쉬는 공기는 쉼 없이 넓은 기낭으로 들어 간다. 기낭은 체강 내 내장 사이로 확 장되어 있고 비상근 사이에 위치하며 추체 를 포함한 거의 모든 뼈 내부로 확장된 길 고 가느다란 게실을 갖는다. 늑골이 위, 앞 으로 회전할 때 기압으로 기낭이 부풀게 되고 강하게 흉골을 압박한다.그때 기낭이 풀무작용을 하게 되어 기관지를 통해 폐 뒤쪽으로 공기를 보낸다. 숨을 내쉴 때는 폐 뒤쪽의 기낭에서 공기가 폐를 통해 폐 앞쪽의 기낭으로 이동해 몸 바깥으로 나간 다. 기낭은 온도조절기로 비행 중에 주위 근육운동에 의해 형성된 과다한 열을 발산 시킨다. 열은 근육에서 기낭 내 공기로 직 접 전달되지 혈류를 통하여 전달되지 않는 다. 조류에서 과다한 열을 방지하는 주요 방어책은 호흡수 증가이다.
기낭이 뼈 내로 확장된 것은 공기 중에서 부력을 더 주기 때문에 새의 특이한 부력 의 감소로 나는 동안 에너지를 보존하며, 기낭 내 더운 공기로 부력의 효과가 증가 된다.(참고 : 척추동물의 비교해부학, 서울 외국서적, 1990)
5) 배설 및 생식계
(1) 신장은 골반의 안쪽에 위치하며, 포유류에 비해 아주 작다.
반고체 상태의 요산(uric acid)으 로 질소노폐물을 배출한다.
(2) 물을 적게 섭취하기 위해 질소의 60% 이상을 요산의 형태로 배출하며, 배설강을 통하여 수분을 어느 정도 재흡수한다.
(3) 어릴 때는 배설강의 뒤쪽에 있는 파부리키우스낭(bursa of Fabricius)이 있어 포유류의 골수와 같이 조혈작용(B cell 생성)에 관여하지만 성장에 따라 퇴화한다.
Like the reptiles, birds are primarily
uricotelic, that is, their kidneys extractnitrogenous wastes from their bloodstream and excrete it as uric acid instead of urea or ammonia via the ureters into the
intestine. Birds do not have a urinary bladder or external urethral opening and uric acid is excreted along with feces as a semisolid waste. However, birds such as hummingbirds can be facultatively
ammonotelic, excreting most of the
nitrogenous wastes as ammonia. They also
excrete creatine, rather than creatinine like
mammals. This material, as well as the
output of the intestines, emerges from the
bird's cloaca. The cloaca is a multi-purpose
opening: waste is expelled through it, birds
mate by joining cloaca, and females lay
eggs from it. In addition, many species of
birds regurgitate pellets.
(4) 자웅이체이며, 대부분의 수컷은 외부 교미기관이 없는 대 신에 배설강의 정액낭(semenal glomera)에 정액을 저장 하고 있다가 교미(copulation) 시 암컷의 배설강에 집어넣 어 체내수정을 한다.
(5) 수컷의 정소는 내부로 함입되어 있으며, 암컷의 난소는 왼 쪽 만 잘 발달되어 있다.
(6) 교미 후 암컷의 저정관(sperm storage tubule)에 정자가 머물러 있다가 한 개씩 수정되어 알을 낳는다. 일반적으로 둥지(nest)를 틀고 산란하며 포란(incubation)하여 부화 된 후 깃털이 자라 날 수 있을 때까지 새끼를 키운다
(fledging).
Egg tooth
In some egg-laying animals, the egg tooth is a small, sharp, cranial protuberance used by offspring to break or tear through the egg's surface during hatching. It is present in most birds and reptiles. Some lizards and snakes develop a true tooth that is shed after use; other reptiles and birds generally develop an analogous epidermal horn that is reabsorbed or falls off.
In birds, the process of breaking open the eggshell is commonly referred to as pipping. Chicks have a pipping muscle on the back of their necks. It is this muscle which gives them the strength to force the egg tooth through the inner membrane of the eggshell. When a chick becomes too large to absorb oxygen through the pores of its eggshell, it uses its egg tooth to peck a hole in the air sac located at the flat end of the egg. This sac provides a few hours worth of air, during which the chick breaks through the eggshell to the outside. The egg tooth falls off several weeks after hatching.
Baby snakes generally hatch from eggs with tough, leathery shells. A baby snake's egg tooth tears a hole directly through the shell, and falls off the first time the snake sheds its skin. Lizards have similarly leathery eggshells.
A baby crocodile has an egg tooth on the end of its snout. It is a tough piece of skin which is totally reabsorbed less than two months after hatching. Crocodile eggs are similar to those of birds in that they have an inner membrane and an outer one. The egg tooth is used to tear open the inner membrane; the baby crocodile can then push its way through the outer shell. If conditions are particularly dry that year, the inner membrane may be too tough for the crocodile to break through, and without
assistance it will simply die inside the egg. Generally, however, the mother crocodile is there to help free it.
6) 신경계 및 감각기관
(1) 대부분 주행성(diurnal)으로 시력이 잘 발달하였으며, 장거 리 이동을 위한 방향 판단력이 있다.
(2) 후각은 잘 발달되어 있지 않으며, 청각은 제한된 범위의 소리만 들을 수 있다.
(3) 일반적으로 군집생활(flock)을 하며 번식을 위한 구애행동 (courtship)을 한다.
(4) 빛에 대한 반응성이 아주 민감하여 생식, 철에 따른 이동, 털갈이 등에 관한 호르몬 작용은 빛의 자극에 영향을 받는다.
Nervous system and migration of birds
The nervous system is large relative to the bird's size. The most developed part of the brain is the one that controls the flight-related functions, while the cerebellum coordinates movement and the cerebrum controls behaviour patterns, navigation, mating and nest building.
Most birds have a poor sense of smell with notable exceptions including kiwis, New World vultures and tubenoses.
The avian visual system is usually highly developed.
Birds possess ultraviolet (UV) sensitive cone cells in the eye as well as green, red and blue ones. This allows them to perceive ultraviolet light, which is involved in courtship.
The eyelids of a bird are not used in blinking. Instead the eye is lubricated by the nictitating membrane, a third eyelid that moves horizontally. The nictitating membrane also covers the eye and acts as a contact lens in many aquatic birds.
Most birds cannot move their eyes, although there are exceptions, such as the Great Cormorant.
The avian ear lacks external pinnae but is covered by feathers.
A few species are able to use chemical defenses against predators; some birds can eject an unpleasant oil against an aggressor, and some species have a powerful neurotoxin in their skin and feathers.
Many bird species migrate to take advantage of global differences of seasonal temperatures, therefore optimising availability of food sources and breeding habitat. These migrations vary among the different groups.
The ability of birds to return to precise locations across vast distances has been known for some time. Birds navigate during migration using a variety of methods. For diurnal migrants, the sun is used to navigate by day, and a stellar compass is used at night by internal clock.
A mystery disease is killing penguins in Antarctica.
Australian scientists have found over 100 penguins dead near their Mawson base.
They fear there could be many more. It is not unusual to find one or two dead penguins in a colony, but this kind of large-scale mortality is rare. The scientists fear an unknown disease is responsible and are concerned that it could spread.
They have restricted human access to the penguins.
They are also disinfecting boots and clothing after leaving the area. Blood and tissue samples are being taken from the birds and will be sent by ship for analysis in Australia in the next few days. The penguins affected are called Adelie penguins (Pygoscelis adeliae) and they are among the most abundant of all the penguins in the Antarctic, so the species is under no imminent threat.
There are about 15,000 in the Australian colonies at Mawson and over two million worldwide. But their numbers have been declining here in Antarctica and it is thought that climate change may be to blame.
They are losing some of the ice that is their natural habitat. Keith Reid, an expert in penguins at the British Antarctic Survey, says there is no cause for immediate alarm at the disease outbreak. "The Australians are very concerned about the potential for humans introducing disease into penguin colonies. But if this was an externally introduced disease, it would go through a colony extremely rapidly."
He said one possibility was that skuas (Antarctic seabirds) travelling large distances while scavenging around the oceans could introduce disease into a penguin colony.
It has also been a bad year for the thousands of Emperor penguins living near the British base at Halley.
The ice broke up early this year, before the chicks were old enough to fend for themselves. And it is thought that most of them have drowned or died of hypothermia.
5. 수생포유류
1) 외부형태 및 골격계
(1) 수생포유류는 물범류(Phocidae ; true seals), 물개류
(Otariidae ; eared seals), 그리고 해마류(Odobenidae ;
walruses)가 속하는 기각류(pinnipeds), 고래(whales)와 돌고 래(dolphins와 porpoise)가 속하는 고래류(cetaceans), 해우 (manatee ;
Trichechus
spp.)와 듀공(dugong ;Dugong
dugon
)이 속하는 해우류(sirenians), 그리고 해달(sea otter ;Enhydra lutris
)과 북극곰(polar bear ;Ursus maritimus
) 등 이 있다.Pinnipeds (from Latin pinna, wing or fin, and ped-, foot) or fin-footed mammals are a widely distributed and diverse group of semi-aquatic marine mammals comprising the families Odobenidae (the walrus ; 바 다코끼리), Otariidae (eared seals, including sea lions and fur seals ; 바다사자 와 물개), and Phocidae (earless seals, common seal ; 바다표범).
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in seventeen genera. They vary in size from 1.2 m (4 ft) and 40 kg (90 lb) (Maui's Dolphin), up to 9.5 m (30 ft) and 10 tonnes (9.8 LT; 11 ST) (the Orca or Killer Whale). They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating fish and squid. The family
Delphinidae is the largest in the Cetacea, and relatively recent: dolphins evolved about ten million years ago, during the Miocene. Dolphins are considered to be amongst the most intelligent of animals and their often friendly appearance and seemingly playful attitude have made them popular in human culture.
Porpoises(쇠물돼지) are small cetaceans of the family Phocoenidae; they are related to whales and dolphins.
They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen. The most obvious visible difference between the two groups is that porpoises have flattened, spade-shaped teeth distinct from the conical teeth of dolphins, and shorter beaks.
The Blue Whale (흰긴수염고래 ; Balaenoptera musculus) is a marine mammal belonging to the suborder of baleen whales (called Mysticeti). At up to 32.9 metres (108 feet) in length and 172 metric tonnes (190 short tons) or more in weight, it is the largest animal ever to have existed
Sirenia (commonly referred to as sea cows) is an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. Four species are living, in two families and genera. These are the dugong (1 species) and manatees (3 species excluding a possible fourth species, the Dwarf Manatee).
Sirenia also includes Steller's sea cow, extinct since the 18th century, and a number of taxa known only from fossils. The order evolved during the Eocene, more than 50 million years ago.
Sirenia, commonly sirenians, are also referred to by the common name sirens, deriving from the sirens of Greek mythology. This comes from an urban legend about their discovery, involving lonely sailors mistaking them for mermaids.
(2) 가슴과 배 사이에 근육성의 가로막(횡격막)이 있다. 피부는 털로 덮여 있다.
(3) 목은 일반적으로 굵고 짧으며, 고래의 경우 경추는 서로 융 합되어 목을 움직이지 못한다. 꼬리는 수평으로 뻗은 지느러 미(fluke) 형태로 상하운동으로 유영한다.
(4) 앞다리는 가슴지느러미로 변하였으며, 지느러미 속에는 다 섯 개의 발가락 골격을 가지고 있다.
(5) 뒷다리가 없으며, 고래의 경우 흔적기관(vestigial
structure)인 골반(pelvis)을 가진다. 그리고 수염고래나 향유고래(sperm whale ;
Physeter macrocephalus
)의 경 우 퇴화된 뒷다리(rudimentary hind limb)를 가진다.(6) 고래의 경우 등의 피부가 볼록하게 솟아 생긴 등지느러미 (dorsal fin)를 갖는다.
○
The body is fusiform. The forelimbs, also called flippers, are paddle-shaped. The end of the tail holds the fluke, or tail fins, which provide propulsion by vertical movement. Although whales generally do not possess hind limbs, some whales (such as sperm whales and baleen whales) sometimes have rudimentary hind limbs; some even with feet and digits. Most species of whale bear a fin on their backs known as a dorsal fin.
The neck vertebrae are fused in most whales, which provide stability during swimming at the expense of flexibility. They have a pelvis bone, which is a vestigial structure.
흔적기관으로 일컬어지는 뼈로는 고래의 골반 뼈가 있다. 다른 동물의 골반 뼈가 발견되는 부분에 이 뼈가 위치해 있다. 이 뼈는 흔적기관으로 불린다. Awbrey (1983)는 고래의 골 반 뼈에 관한 진화론적 논쟁을 요약하였다.
“고래류는 흔적기관의 예를 갖고 있다. 골반은 작아졌고 더 이상 뒷다리를 척추와 연결 짓 지 않는다. 두 개의 작은 뼈는 생식과 배변 근육을 지지하는 기능을 할 뿐이다. 그 사실은 설 계 혹은 진화 중 그 어느 것에도 적합할 수 있다.”
그는 그 문장을 정당화하기를 고래들이 때때로 비정상적인 다리뼈를 만들기도 하기 때문에 오직 진화론자들만이 줄어든 골반 뼈와 다리뼈의
흔적에 대해 가장 잘 들어맞는(parsimonious) 설명을 제공할 수 있다고 하였다.
여러 연구자들은 실제로 이 뼈들이 그 내부기관을 지지하며, 여러 근육을 위한 접촉점으로 사용된다 는 것을 발견해 왔다. 특히 골반은 생식기 근육의 부착점으로 사용되며, 여러 고래의 경우 그러한 사 례가 확인되었다.
* 고래의 흔적기관(골반뼈) *
2) 피부
(1) 피부에는 땀샘, 지방샘, 젖샘이 있다.
(2) 고래의 피하조직은 두꺼운 지방층 (blubber)이 있어, 체온유지와 에너 지 물질의 저장을 겸한다.
(3) 고래는 아래턱에 감각모(sensory hair) 외에는 털이 없으나, 물개는 털을 가지며
땀샘이나 지방샘(sebaceous gland)이 있다.
(4) 고래의 경우 땀샘이 없는 대신에 지방층이 없는 지느러미 부위 에서 더운 동맥혈과 차가운 정맥혈이 서로 반대 방향으로 흘러
(countercurrent heat exchanger) 열을 교환하여 체온 조절을 한다.
Reuters W orld News Expres s .flv
Fur seals have both blubber and a specially adapted fur coat, including outer guard hairs that repel water and a layer of insulating underfur. For this reason they were particularly prized by sealers. Many species were nearly hunted to extinction.
For most pinniped species molting is an annual process of replacing worn fur (and in some cases, skin) that temporarily grounds them. While molting,
thermoregulation can be compromised, so some species, such as Elephant seals, fast and remain onshore for a month or more.
In many species, pups are born with a natal coat of a different length, texture and/or color than adults. This coat is adapted for the terrestrial, pre-weaning period, either a thick pelage to keep them warm in arctic environments, or a thin layer of fur to keep them cool on summer sands. During their first molt (about 11 days after birth for harp seals) the pups replace this with an adult coat better suited to life at sea. Until this age, pups risk hypothermia and drowning if they spend much time in the ocean.
3) 소화계
(1) 돌고래와 같이 이빨을 갖는 고래(toothed whales ; Odontoceti) 는 원추형의 날카로운 이빨을 가지고 있어 두족류나 어류를 포식하 는 육식성이나, 수염고래와 같이 위턱의 잇몸(gum)에 두 줄의 각 질로 이루어진 수염판(baleen)을 갖는 고래(baleen whales ; Mysticeti)는 크릴 등의 소형 갑각류나 플랑크톤을 섭취하며 수염 판은 먹이를 체와 같이(sieve-like) 걸러주는 역할을 한다.
(2) 양턱에 이빨들이 있는데, 이빨의 수는 종류에 따라 다르다(돌고래 의 경우 200개 이상). 이빨은 앞니(incisors), 송곳니(canines), 앞어금니(premolars), 그리고 어금니(molars)로 분화하였고, 각 종류에 특유의 치식(dental formular)이 있다. 그러나 고래의 경우 다른 포유류와 달리 모든 이빨이 같은 모양을 가진다(homodonty).
Image of a swarm of krill, shrimp-like marine invertebrate animals, that are one of the whale's primary foods.
Baleen hair is attached to baleen plate
* 수염고래의 수염판(baleen plate) *
The baleen whales are characterized by baleen, a sieve-like structure in the upper jaw made of keratin, which they use to filter plankton from the water.
Baleen whales such as humpbacks and blues feed only in arctic waters, eating mostly krill.
They imbibe enormous amounts of seawater which they expel through their baleen plates.
The water is then expelled and the krill is retained on the plates and then swallowed. Whales
do not drink seawater but indirectly extract water from their food by metabolizing fat.
The baleen whales are characterized by baleen, a sieve-like structure in the upper jaw made of keratin, which they use to filter plankton from the water. They are the largest suborder of whale.
The toothed whales have teeth and prey on fish, squid, or both. An outstanding ability of this group is to sense their surrounding environment through echolocation.
(3) 구강과 상부 소화기관(식도와 전위)에 타액선과 점액 분비선 이 발달되어 있지 않으며, 돌고래의 경우 위는 협착부
(esophageal orifice), 전위(forestomach), 주위(fundic chamber) 및 유문부(pyloric
chamber)로 나뉜다.
(4) 고래의 간장은 2엽으로 나누어 지며 육생동물과 비슷하나, 담 낭(gall bladder)이 없다.
Whales are generally classed as predators, but their food ranges from microscopic plankton to very large animals. Toothed whales eat fish and squid which they hunt by use of echolocation. Orcas(=killer whale) sometimes eat other marine mammals,
including whales.
4) 순환 및 호흡계
(1) 허파로 호흡하며 오랫동안 잠수가 가능하도록, 적응되어 있다.
수중의 높은 수압 하에서 호흡 시 산소 흡수를 높이기 위해 말단 세기관지(bronchiole)에 연골과 괄약근(sphincter)이 잘 발달 되어 있고, 많은 혈액과 적혈구를 가지며 근육에는 마이오글로 빈이 풍부하여 더 많은 산소를 한번에 섭취할 수 있다.
(2) 심장은 완전한 2심방 2심실로 되어 있고, 수중에서는 심장박동 수(heart rate)를 낮추어(10-30 회/분) 심장과 뇌를 제외한 조직으로 가는 혈류량을 감소시킴으로서 산소의 소비량을 줄여 잠수를 오래할 수 있게 한다.
(3) 고래는 머리 위의 분기공(blowhole)을 통해 물과 함께 숨을 내 쉬며, 분기공은 머리 속의 관(bone nares=nasal passage)을 통해 기관으로 연결된다. 허파로 호흡을 하며, 물 속에 있을 때 는 분기공이 닫혀져서 물이 들어가지 않는다.
* 고래가 분수처럼 물을 뿜는 이유는 잠수를 마치고 수면으로 올라와 폐 속의 공
기를 바꾸기 위해 코 구멍에 있는 물과 기도에 있는 공기를 바깥으로 내뱉기 때
문이다.
As mammals, whales breathe air and must surface to get oxygen. This is done through a blowhole. Many whales also exhibit other surfacing behaviours such as breaching and tail slapping.
Because of their environment (and unlike many animals), whales are conscious breathers: they decide when to breathe. All mammals sleep, including whales, but they cannot afford to fall into an unconscious state for too long, since they need to be conscious in order to breathe in the water. It is thought that only one hemisphere of their brains sleeps at a time, so that whales are never completely asleep, but still get the rest they need. This is thought because whales often sleep with only one eye closed
5) 배설 및 생식계
(1) 배설계의 신장은 후신형(metanephros)이고 요도(urethra)는 보통 방광에서 열린다. 비뇨생식공(urogenital opening)과 항문 (anus)은 오리너구리(platypus)를 제외하고는 따로 열린다.
(2) 신장은 소신이 다수 집합(300-3000개)되어 있는 분엽신
(lobular kidney)으로 되어 있으며, 신장에 연결된 방광은 비교 적 작고, 체내의 여분의 염류는
변과 함께 배설된다.
(3) 자웅이체로 태반생식을 하며 어린 새끼는 젖으로 양육하며, 체 내수정을 한다. (예외 ; 오리너구리(platypus)난생이며, 부화한 새끼는 젖으로 키운다, 캥거루(유대류)-태반을 형성하지 않고 새끼는 발생 초기에 태어나며, 육아낭
(marsupium=brood pouch) 에서 일정 기간 동안 성장한다).
(4) 고래는 육상동물과 유사한 생식기관을 가 지며, 교미에 의해 번식하며, 임신기간은 10개월 전후이다. 하복부에 있는 젖꼭지로 농도가 높은 젖(99%가 지방과 단백질)을 먹인다.
Females give birth to a single calf. Nursing time is long (more than one year in many species), which is associated with a strong bond between mother and young. In most whales reproductive maturity occurs late, typically at seven to ten years. This mode of reproduction spawns few offspring, but provides each with a high probability of survival in the wild.
The male genitals are retracted into cavities of the body during swimming, so as to be streamlined and reduce drag and to prevent injury. Most whales do not maintain fixed partnerships during mating; in many species the females have several mates each season. At birth newborn are delivered tail-first, minimising the risk of drowning. Whale cows nurse by actively squirting milk the consistency of toothpaste into the mouths of their young preventing loss to the surrounding aquatic environment.
* 오리너구리 (duckbill=platypus )(단공류 : Ornithorhynchus) *
a platypus egg와 newborn platypuses with mother
a young platypus와 platypus youth
6) 신경계 및 감각기관
(1) 뇌는 고도로 발달하여 12쌍의 뇌신경(cranial nerve)을 가지 며, 뇌에 후구(olfactory bulb)의 흔적만 있다.
(2) 고래는 표피에 판층소체(perineural epithelium)라고 하는 말 초신경(peripheral nerve)이 다수 분포되어 있다.
(3) 움직일 수 있는 눈꺼풀이 있으며, 물개 등에서는 해수의 자극으 로부터 각막(cornea)을 보호하기 위해 각막이 각화되어 있다.
(4) 귓바퀴(earflap)는 없으며, 외계와 고막(eardrum=tympanic membrane)으로 접하지 않으므로 귓구멍(earhole)은 피부 밑 이 끊어져 있다.
Whales' ears have specific adaptations to their underwater environment. In humans, the middle ear works as an impedance matcher between the outside air’s low impedance and the cochlear fluid’s high impedance. In aquatic mammals such as whales, however, there is no great difference between the outer and inner environments. Instead of sound passing through outer ear to middle ear, whales receive sound through their lower jaw, where it passes through a low-impedance, fat-filled cavity.
Figure. Whale’s ear bone of inner ear
(5) 돌고래의 경우, 청각을 좌우하는 와우신경(cochlear nerve)이 발 달하였으며, 박쥐와 같이 성대(phonic lips)로 초음파를 단속적으 로 내어 물체에 부딪쳐 반사된 초음파를 아래턱에 있는 이골과 연 결된 지방 조직(mandibular fat)을 통해 내이로 포착하여 그 물체 의 거리, 방향, 크기 등을 감지하여 행동하며(반향정위 ;
echolocation), 서로 간의 의사소통에도 이용된다.
(6) 머리 앞부분에는 구형의 지방 조직(melon)이 있는데, 음파를 외 부로 발산하는데 있어서 외부와 같은 조건을 만들어주어 음파가 잘 전달되게 하는 역할을 한다.
(7) 고래의 후각은 다른 포유류에 비 해 퇴화되어 있으며, 미뢰
(gustatory bud)에 상응하는 화 학수용기가 전혀 없어 맛을 느끼 지 못한다. 대신에 입 주위에 발 달한 감각모로 촉각의 기능을 한 다.
Echolocation in toothed whale
Echolocation is a sensory sonar system that dolphins use for communication and for detecting other animals, food and obstacles.
Toothed whales emit a focused beam of high-frequency clicks in the direction that their head is pointing.
Sounds are generated by passing air from the bony nares through the phonic lips. These sounds are reflected by the dense concave bone of the cranium and an air sac at its base. The focused beam is modulated by a large fatty organ known as the 'melon'. This acts like an acoustic lens because it is composed of lipids of differing densities. Most toothed whales use clicks in a series, or click train, for echolocation, while the sperm whale may produce clicks individually.
Echoes are received using complex fatty structures around the lower jaw as the primary reception path, from where they are transmitted to the middle ear via a continuous fat body. Lateral sound may be received though fatty lobes surrounding the ears with a similar acoustic density to water.
How dolphins make sounds The naso-pharynges are similar to vocal cords with air sacs above and below them. The dolphin apparently shuttles air between the top and bottom air s a c s a n d p a s t t h e n a s o - pharnyges to make sounds. The diagram left shows roughly how sounds are made by the dolphin:
Inhaling - the blowhole is open and the air is sucked into the lungs (top drawing). Vocalizing - the blowhole closed and air from the lungs is forced into an air sac near the top to the head.
As the air sac fills, the forehead swells (middle right drawings).
Then the dolphin closes the lip of the air sac and releases air back toward the lungs (bottom drawing). The air sac lip (one of four naso-pharynges) then produces a sound (much like releasing air from a balloon).
phonic lips of sperm whale
Instead of sound passing through outer ear to middle ear, whales receive sound through their lower jaw, where it passes through a low-impedance, fat-filled cavity.
뉴질랜드 남섬 페어웰스피트의 해변에서 모래사장 위에 갇혀 죽 은 고래들을 노동자들이 치우고 있다. 파일럿 고래 37마리가 10 일 뉴질랜드 오클랜드 북부 루아 카카 해안가에서 '집단 자살'을 했다. 애초 77마리가 자살하기 위해 뭍으로 올라왔으나 40마리 는 구조대원들이 중장비를 동원 해 바다로 다시 밀어 넣어 살려 냈다. 전문가들은 고래나 물개 같은 해양 동물이 육지로 올라와 스스로 목숨을 끊는 현상을 '스 트랜딩(stranding)'이라고 부른 다. 그 원인을 어떤 이유에선가 생명의 위협을 느끼기 때문이라 고 설명한다. 고래는 폐렴 등에 걸려 자기가 죽어간다는 사실을 인식할 때 뭍으로 올라와 자살한 다는 연구 결과도 있다. [루아카 카 AFP=연합뉴스]
A beached whale is a whale that has stranded itself on land, usually on a beach. Beached whales often die due to dehydration, the body collapsing under its own weight, or drowning when high tide covers the blowhole. Single live strandings are often the result of illness or injury, which almost inevitably end in death absent appropriate human intervention.
'머리 둘, 꼬리 둘에 몸은 하나 '
연합뉴스|2014.01.09(AP=
연합뉴스)
멕시코 국립자연보호위원회 (CONANP)는 지난 5일 멕시 코 바하 반도의 오호 데 리에 브레 해안에서 발견된 새끼 귀신고래 사체의 머리 쪽 사 진(위)과 꼬리 쪽 사진(아래) 을 8일(현지시간) 공개했다.
위원회 측은 이 고래가 머리 와 꼬리는 각각 두 개지만 복 부가 붙어있었다고 밝혔다.
< 저작권자(c)연합뉴스.
