Reptiles do not have gills. Instead, they have well-developed lungs that are used for respiration. They have a dry and scaly skin, and they reproduce terrestrial eggs that are enclosed in four membranes.

C. gills

A mass extinction occurred at the end of the Cretaceous Period. This led to the disappearance of dinosaurs.

A. Cretaceous Period

As ectotherms, reptiles are able to regulate their body temperature through their interaction with the environment.

B. ectotherm

Turtles and tortoises, which are members of the order Testudines, have protective shells called the carapace (dorsal part) and the plastron (ventral part).

C. turtles and tortoises

According to the diagram, letter Y represents the allantois. This membrane stores the waste products of an embryo.

C. allantois

Birds are the only living animals that have feathers.

B. feathers

The large chest muscles found in birds are necessary for flight. This structure helps the bird propel forward and downward as they fly.

D chest muscles

Since seed-eating birds lack a teeth, they have a gizzard, which mechanically breaks down the food. Gizzards contain pieces of gravel and stones that crush the food particles.

B. gizzard

Similar to reptiles, birds are unable to excrete ammonia directly. Instead, they convert ammonia into uric acid. First, the urine is reduced to crystals of uric acid while the excess water is absorbed by the cloaca. Then, the crystals form a pasty white solid.

C. uric acid

The respiratory system of a bird works in such a way that there is only a single flow of air.

C. maintain a one-way flow of air

**Reptiles** are vertebrate species that have a scaly skin, paired well-developed lungs, a double-loop circulatory system, and eggs that contain several membranes for protection. The skin of the reptiles undergoes periodic shedding as they grow because the shedding of skin allows for further growth. Improper or incomplete shedding may happen because of trauma, disease, malnutrition, or a presence of parasites.

The earth’s climate cooled at the end of the Carboniferous period and became less humid. Lakes and swamps dried up reducing the habitat for amphibians. These conditions led to the first great adaptive radiation of reptiles. The changes in the environment had a negative impact on the survival of many amphibian populations.

A dramatic series of natural disasters occurred at the end of the Cretaceous period. These included an asteroid collision that produced massive forest fires and dust clouds. There were also volcanic eruptions and lava flows as well as a drop in sea levels. These events are believed to have caused the mass extinction.

Reptiles are considered **ectotherms**. These animals rely on behavior and their interaction with the environment to aid them in regulating their body temperature. Most reptiles like turtles, lizards, and snakes bask in the sun during the day to keep themselves warm and to cool down they usually move to a shady place, burrow underground, or stay in the water for a swim.

Reptiles have spongy lungs that provide more gas exchange areas. This is helpful in the respiration aspect as reptiles cannot exchange gasses through the skin as amphibians do. They have strong muscles which allow the chest cavity to expand and enable them to inhale and exhale for respiration.

Reptiles reproduce amniotic eggs that are enclosed in a shell and membranes. The amnion, which surrounds the embryo, provides a watery environment that serves as a cushion. Because of these conditions, a reptilian egg can develop without drying out.

Turtles are species characterized by having a shell that is built into their skeleton. A turtle shell consists of two parts: a dorsal part called the carapace, and the ventral part called the plastron. The backbone is the center of the carapace. The two parts have openings where the turtle’s limbs and head can protrude.

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**Crocodilians** are under the order Crocodilia. This order includes all species of alligators, crocodiles, and caimans. These organisms are easily identified because of the presence of their long broad snout and squat semblance.

Crocodiles are very fierce organisms and they are very protective of their young ones. Female crocodiles guard their eggs against predators and once these eggs are hatched, the mother will bring this hatchling to a nursery and watch over it all throughout its life until it is ready to hunt and live independently.

The beak or bill of the birds is adapted to the type or kind of food they eat. Insect-eating birds have short, fine beaks that can prey on small insects like ants and bugs, while seed-eating birds have short, thick beaks. Carnivorous birds like eagles and vultures have strong hooked beaks, and nectar-eating birds have long, thin beaks to help them pick up nectars from flowers. Lastly, fruit-eating birds have large, long beaks that enable them to gather fruit from tree branches.

Therefore, the answer is a seed-eating bird.

During nesting season, a substance which is rich in protein and fat is produced in the crop. Pigeons regurgitate this substance and feed their young with it.

The air sacs, which are found in the respiratory system of a bird, ensure that the air goes in a one-way flow. As soon as the air is inhaled by the bird, it goes into the air sacs then into the body cavity and the bones. Once the air goes inside the lungs, the lungs are exposed to oxygenated blood.

Flying birds have a skeletal system that is adapted for flight. The bones of the bird’s wings are considered homologous to those front limbs of other vertebrates like humans, though they have different structures and appearances.

Flying birds have large bones and collarbones that are fused together to create a more rigid structure. These bones are designed to form a sturdy frame that creates an attachment site for their strong muscles used for flight.

Similar to reptiles, birds lay amniotic eggs that are enclosed in a hard outer shell and membranes. The amnion, which surrounds the embryo, provides a watery environment that serves as a cushion. On the other hand, the yolk sac is attached to the embryo. The yolk sac contains the yolk which serves as the food and nutrient supply for the embryo. The adult birds incubate their eggs until they are ready to be hatched. Once a chick is ready to hatch, a hole is made in the shell using the chick’s bill. The chick pushes and pokes the eggshell until it breaks open.

As endotherms, birds have a high metabolism rate which produces body heat. This heat keeps their bodies warm. In addition, the bird’s feathers help in insulating its body. Because of these conditions, birds are likely to survive a cold environment.

Birds have a well-developed nervous system and sense organs. The brain of the birds can easily interpret and coordinate responses to incoming stimuli. They have a **cerebrum** that controls various behaviors like flying, nest building, parenting, courtship, and mating. Moreover, they have a **cerebellum** which functions to create coordinated movements, and other body processes.

**Birds** are known to inhabit various environments and they have a wide range of species. The list below will show you some commonly known groups of bird species.

1. Pelicans – These birds are usually found in aquatic habitats and they have four toes that are connected by a web. These toes are adapted in order for them to thrive in these kinds of environments. Examples: boobies, and cormorants

2. Birds of Prey or the *raptors* – These bird species are known to be fierce predators having hooked beaks to capture their prey. These species are all carnivorous. Examples: Eagles and hawks.

3. Parrots – These bird species are known to be colorful and noisy. Their foot is very well adapted to hold their food. They have advanced cognitive ability and they are able to talk. Examples: Cockatoos, macaws

4. Cavity-nesting birds – These birds are multicolored and show the behavior of making tree holes to serve as their nests. Examples: Woodpeckers, and toucans.

5. Perching birds (Passerines) – These are the largest group of birds. These birds have four toes, in which three toes are directed forward and one backward. Many of the bird species found in this group are songbirds. Examples: Mockingbirds, and cardinals.

6. Herons and their relatives – These birds, like the pelicans are also adapted to wading in various aquatic habitats, They have long legs, and long necks.

7. Ostriches – These are flightless and the largest species of birds that have. Because these species cannot fly, they only move by walking, running, or swimming. Examples: Ostriches, and kiwis

Most bird species migrate long distances. They often travel kilometers of open land and seas. Migration usually happens seasonally as they need to find a good environment because of the changing seasons. Birds find their way through the use of stars, and other celestial bodies–they used them as guides to the place they wanted to go. Other species use landmarks and cues from the magnetic field of the Earth.

In order for a bird to fly, it must have strong and large chest muscles. Since the Archaeopteryx does not have this structure, it is unable to fly efficiently; hence, it is regarded as a poor flier. Although it is unable to fly, its wings are capable of flapping. If the wings are flapped, it will help gain speed as it runs. Since its wings have evolved from the limbs of its ancestor, another possible use of this structure is for abducting its prey.

Here are the questions that can be asked in order to learn more about birds’ diet and energy needs:

1. What is the structure of the bird’s bill?
(Short bills are usually insect-eating birds; thick bills are seed-eating birds; hooked bills are meat-eating birds; thin bills are used for feeding on flowers, or worms)

2. What is the size of the bird?
(Small birds lose body heat faster than larger ones; therefore, small birds eat more)

**Snakes** are a group of reptiles that belong to the order “Squamata.” Snakes have lost their legs during the course of their evolution. Snakes vary in size from as small as an earthworm to a large python of about 8 meters long.

The warm tropical island would have more reptiles than the cooler island. Reptiles thrive in warmer environments including those with moist climates. The cooler island may be too cool for the reptiles to function properly.

Please review explanation

Herons and their relatives are birds like the pelicans that are also adapted to wading in various aquatic habitats, They have long legs, and long necks that are very useful in hunting aquatic animals like fish for food. These long legs also serve to support them as they stand and walk in muddy or sandy waters.

According to the question, the animal is endothermic. It has two legs, modified front limbs (wings) and a four-chambered heart. These features are found in a bird.

The animal that was described in the statement is a bird.

The muscles that bird uses most often contain the greatest amount of protein called **myoglobin**. The chest muscle of a duck consists of more myoglobin than chickens. This shows us that the ducks are unable to fly as they have higher levels of myoglobin, and this protein is used to store more oxygen during their dives in the water. On the other hand, chickens are able to fly for a short distance as they consist of less amount of myoglobin.

Birds and reptiles have similar features such as a constant body temperature, legs that are covered with scales, and bones that support front and hind limbs. They both reproduce amniotic eggs and excrete wastes in the form of uric acid. However, the only thing that sets the difference is the presence of feathers in birds.

Due to these similarities and the discovery of the fossils of the Archaeopteryx, scientists have hypothesized that birds and reptiles share the same ancestor.

The seabirds brood in colonies to resist the attack from predators. They mumble in groups to scare away the predators like owls. An experiment is to be designed to know whether the young birds are able to distinguish their parental calls from others in the colony.

**Hypothesis**:

The sea birds in the brooding season are to be observed keenly. The parental seabirds forage and leave their younger ones in the nest. They return to the nests by making use of cues like landmarks and the magnetic field of Earth. The biological rhythm in the younger ones is set up in such a way that they register the time of their parent’s arrival. This can be made used to study their ecological behavior.

**Proposed experiment**:

A specific set of birds in the family are to be observed. The chirps of the parental birds alone, the mixed chirps of all the birds in the colony, and that of other species in the colony are recorded individually. The next step is to observe the young ones reaction at the various types of chirps at the time of arrival of their parental ones. The response of the young ones is meticulously observed and recorded for analysis. This can give an idea of their ecological behavior.

Here is a sample scale diagram using the information from the table about snake descriptions: