Which Animals Have a Notochord?
A species of African caecilian,. Like fish, amphibians are ectothermic vertebrates. Buccal cavity is narrow and some what and dorsoventrally flattened 2. They have bilateral symmetry and an internal skeleton of cartilage or bone. Learn more about Zoology. What Animal Has the Largest Teeth?
What Animals Live in the Temperate Forests?
Mucous glands are absent. Oesophagus is a long thin walled tube. It is clearly marked off from the pharynx as well as stomach.
The oesophagus is dilated into a thin-walled sac the crop. It secrete pigeon milk in both sexes and used to feed the young birds. The wall of oesophagus is produced into the cardiac stomach to form cardiac valve. Stomach is a sac- like structure. Its anterior part is cardiac stomach and posterior part is pyloric stomach. At the end of pyloric stomach a small constriction is present.
It possesses a pyloric sphincter. Stomach is divided into a glandular proventriculus and posterior muscular gizzard. Gizzard acts like grinding apparatus. Stomach is divisible into cardiac, fundic and pyloric parts. Pyloric stomach contains pyloric valve. Intestine is differentiated into duodenum and ileum. Intestine very long and very much coiled because is a herbivorous animal Same structures are present. But the bile duct and pancreatic ducts open separately into the proximal and distal ends of the duodenum respectively.
A single rectal caecum is present. An ilio-colic valve is present at the junction of the small intestine and large intestine or colon. At the junction of these portions, a spiral shaped vermi form appendix is present. At the regular intervals of the colon shows pocket-like pouches - 'Haustra'. Colon shows longitudinal muscle folds taeniae'. Cellulose enzyme is produced. Cloaca is common opening for digestive'and urinogenital ducts.
It is divided into coprodaeum,urodaeum, and proctodaeum. Cloaca is large and divided into the same parts. On the dorsal side of the proctodaeum a thick walled blindsa"Bursa fabricii" is present.
It becomes degenerated in the adult and is known as cloacal thymus. Liver is bilobed gland. The right lobe has a gall bladder. Liver is bilobed dark red gland. Gall Bladder is absent. Separate bile ducts are formed.
Although different snake species reproduce in different ways, all snakes use internal fertilization. The male uses sex organs stored in its tail to transfer sperm to the female. Most species of snakes lay eggs, and most species abandon these eggs shortly after laying. All snakes are strictly carnivorous, eating small animals including lizards, other snakes, small mammals, birds, eggs, fish, snails or insects. Because snakes cannot bite or tear their food to pieces, prey must be swallowed whole.
The body size of a snake has a major influence on its eating habits. Snakes have a very flexible lower jaw, the two halves of which are not rigidly attached. They also have many other joints in their skull, allowing them to open their mouths wide enough to swallow their prey whole. Some snakes have a venomous bite, which they use to kill their prey before eating it.
Other snakes kill their prey by strangling them, and still others swallow their prey whole and alive. After eating, snakes enter a resting stage, while the process of digestion takes place. Crocodilia, containing both alligators and crocodiles, is an order of large reptiles.
Reptiles belonging to Crocodilia are the closest living relatives of birds. Reptiles and birds are the only known living descendants of the dinosaurs. Think about how organisms with the same ancestors can evolve to be so different.
The basic crocodilian body plan Figure below is a very successful one, and has changed little over time. Modern species actually look very similar to their Cretaceous ancestors of 84 million years ago. Crocodilians have a flexible, semi-erect posture. All crocodilians have, like humans, teeth set in bony sockets, but unlike mammals, they replace their teeth throughout life.
Crocodilians also have a secondary bony palate that enables them to breathe when under water, even if the mouth is full of water. Their internal nostrils open in the back of their throat, where a special part of the tongue called the palatal valve closes off their respiratory system when they are underwater, allowing them to breathe.
Crocodiles and gharials large crocodilians with longer jaws have salivary glands on their tongue, which are used to remove salt from their bodies. Crocodilians are often seen lying with their mouths open, a behavior called gaping. One of its functions is probably to cool them down, but it may also have a social function.
Crocodilians are known to swallow stones, known as gastroliths, which help digest their prey. The crocodilian stomach is divided into two chambers.
The first is powerful and muscular. The other stomach is the most acidic digestive system of any animal. It can digest mostly everything from their prey, including bones, feathers, and horns! The sex of developing crocodilians is determined by the temperature of the eggs during incubation eggs are kept warm before they hatch. This means that the sex of crocodilians is not determined genetically.
If the eggs are kept at a cold or a hot temperature, then their offspring may be all male or all female. To get both male and female offspring, the temperature must be kept within a narrow range.
Like all reptiles, crocodilians have a relatively small brain, but the crocodilian brain is more advanced than those of other reptiles. As in many other aquatic or amphibian tetrapods, the eyes, ears, and nostrils are all located on the same "face" in a line one after the other. They see well during the day and may even have color vision, but they have excellent night vision.
A third transparent eyelid, the nictitating membrane , protects their eyes underwater. While birds and most reptiles have a ring of bones around each eye which supports the eyeball, crocodiles lack these bones, just like mammals and snakes.
The eardrums are located behind the eyes and are covered by a movable flap of skin. This flap closes, along with the nostrils and eyes, when they dive, preventing water from entering their external head openings. The middle ear cavity has a complex of bony air-filled passages and a branching tube. The upper and lower jaws are covered with "sensory pits," which hold bundles of nerve fibers that respond to the slightest disturbance in surface water. Crocodiles can detect vibrations and small pressure changes in water, making it possible for them to sense prey and danger even in total darkness.
Like mammals and birds, and unlike other reptiles, crocodiles have a four-chambered heart. But, unlike mammals, blood with and without oxygen can be mixed. Turtles are reptiles in the order Testudines. If you have seen turtles before, what is the most noticeable thing about them? Most turtle bodies are covered by a special bony or cartilaginous shell developed from their ribs. About species are alive today, and some are highly endangered. Like other reptiles, turtles are poikilothermic , meaning their temperature changes in response to their environment.
Turtles are broken down into two groups, based on how they bring their neck back into their shell:. Although many turtles spend large amounts of their lives underwater, they can also spend much of their lives on dry land and breathe air. Turtles cannot breathe in water, but can hold their breath for long periods of time. Turtles must surface at regular intervals to refill their lungs. Turtles lay slightly soft and leathery eggs, like other reptiles. The eggs of the largest species are spherical, while the eggs of the rest are longer in shape Figure below.
Most turtles that spend most of their life on land have their eyes looking down at objects in front of them. Some aquatic turtles, such as snapping turtles and soft-shelled turtles, have eyes closer to the top of the head. These species of turtles can hide from predators in shallow water, where they lie entirely submerged in water except for their eyes and nostrils. Sea turtles Figure below have glands near their eyes that produce salty tears, which remove excess salt taken in from the water they drink.
Turtles have exceptional night vision due to the unusually large number of cells that sense light in their eyes. Turtles have color vision. In some species, temperature determines whether an egg develops into a male or female.
Large numbers of eggs are placed by the female in holes dug into mud or sand. They are then covered and left to grow and develop by themselves.
When the turtles hatch, they squirm their way to the surface and head toward the water. Turtles have a rigid beak and use their jaws to cut and chew food. Instead of teeth, the upper and lower jaws of the turtle are covered by horny ridges. Carnivorous turtles usually have knife-sharp ridges for slicing through their prey. Herbivorous turtles have serrated ridges that help them cut through tough plants. The largest turtle is the great leatherback sea turtle Figure below , which can have a shell length of 7 feet and can weigh more than 2, pounds.
The only surviving giant tortoises are on the Seychelles and Galapagos Islands and can grow to over 4 feet in length and weigh about pounds Figure below. The smallest turtle is the speckled padloper tortoise of South Africa, measuring no more than 3 inches in length, and weighing about 5 ounces. The chief impact of reptiles on humans is their role as predators of pest species. For example, in many different countries, like India, snakes kill rats that can be pests and carriers of disease.
Also, since turtles live for hundreds of years, genetic researchers are examining the turtle's DNA for possible genes involved in a long life. Reptiles also make good pets. In the Western world, some snakes, especially less aggressive species, like the ball python or corn snake, are kept as pets. Turtles, particularly small land-dwelling and freshwater turtles, are also common pets.
Among the most popular are Russian tortoises, Greek spur-thighed tortoises and terrapins. Finally, reptiles play a significant role in folklore, religion and popular culture. The Moche people of ancient Peru worshipped reptiles and often put lizards in their art.
Snakes or serpents are connected to healing and to the Devil. Since snake's shed and then heal again, they are a symbol of healing and medicine, as shown in the Rod of Asclepius Figure below. In Egyptian history, the Nile cobra is found on the crown of the pharaoh.
This snake was worshipped as one of the gods. Name two organs that a turtle or a snake have that closely resemble organs in humans. Why are they similar? Life Sciences in Maine. Introduction to Vertebrates Lesson Objectives Describe the general features of chordates. List the three groups of chordates and their characteristics.
List the general features of vertebrates. Describe the classification of vertebrates. Check Your Understanding What is a invertebrate? What is a vertebrate? Vocabulary cranium endostyle notochord Chordates Did you know that fish, amphibians, reptiles, birds and mammals are all related?
Pharyngeal slits, which help to filter out food particles. An endostyle , which has small hairs and is used to gather food particles and move them along the digestive tract. A post-anal tail, which is present during the lifetimes of some chordates and during the development of others. The chordate phylum is broken down into three subphyla: Urochordata represented by tunicates: Urochordates have a notochord and nerve cord only during the larval stage Figure below.
The urochordates consist of 3, species of tunicates, sessile marine animals with sack-like bodies and tubes for water movement. Cephalochordata represented by lancelets: Cephalochordates have a notochord and nerve cord but no vertebrae, or bones in the backbone Figure below. Cephalochordates consist of 30 species of lancelets burrowing marine animals. Humans fall in this category. In all vertebrates except for hagfish, the notochord is smaller and surrounded by vertebrae.
Vertebrates all have backbones or spinal columns. About 58, species have been described, including many familiar groups of large land animals. A species of carp. Gills help a fish breathe. One of the only eight living species of lobe-finned fish, the lungfish. One of the eight living species of lobe finned fish, the coelacanth. Workers harvest catfish from the Delta Pride Catfish farms in Mississippi. One of the many species of amphibian is this dusky salamander.
A species of African caecilian,. The Pacific giant salamander can reach up to 6 feet in length and weigh up to 66 pounds. A toad, showing typical characteristics of leathery and warty skin, and brown coloration. Notice the powerful muscles in the limbs, and the coverings around the eyes. An Indian gharial crocodile. A corn snake swallowing a mouse.
A Komodo dragon, the largest of the lizards, attaining a length of 10 feet. A species of lizard, showing general body form and camouflage against background. A species of anaconda, one of the largest snakes, which can be as long as 17 feet. We welcome suggested improvements to any of our articles. You can make it easier for us to review and, hopefully, publish your contribution by keeping a few points in mind.
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Digestive and urogenital systems The digestive system of modern reptiles is similar in general plan to that of all higher vertebrates. Sense organs Sight In general construction the eyes of reptiles are like those of other vertebrates. Previous page Circulatory system. Page 9 of Learn More in these related Britannica articles: Reptile s, of which there are few endemic families, have mainly Old World affinities. Those most likely to be seen include lizards of the agamid family, skinks a family of lizards characterized by smooth overlapping scales , crocodiles, and tortoises.
Endemic reptiles include girdle-tailed…. Although amphibian gastrulation is considerably modified in comparison with that in animals with oligolecithal eggs e. Such is not the case, however, in the higher vertebrates that possess eggs with…. The living reptiles belong to four orders: The reptile ear has many different forms, especially within the suborder Sauria lizards , and variations occur in….
Unlike lungfishes and amphibians, reptiles depend entirely on their lungs for respiration. Gills and skin do not provide additional sources of oxygen. Because of the development of a neck…. Reptile s are the first vertebrates that, in an evolutionary sense, have evolved an egg that is truly independent of water.
Indeed, many snakes and lizards have even gone beyond this stage and have attained complete viviparity. It is difficult to generalize about reproductive behaviour…. More About Reptile 41 references found in Britannica articles Assorted References annotated classification In vertebrate: Annotated classification characteristics of chordates In vertebrate: The tetrapods paleontological record In animal: Rise of vertebrates behaviour care for young In animal social behaviour: Social interactions involving the costs and benefits of parental care dormancy In dormancy: Reptiles locomotion In locomotion: Carangiform and ostraciiform locomotion mating In reproductive behaviour: Reptiles patterns of migration In migration: