**Animals** are heterotrophic species that function to carry various living processes including feeding, respiration or breathing, blood circulation, response, and reproduction. These organisms are eukaryotic multicellular, and they lack cell walls. They have high levels of specialization and internal organization which makes them a higher form of species.

Hence, the correct answer is **C**

C

**Animals** are heterotrophic species that function to carry various living processes including feeding, respiration or breathing, blood circulation, response, and reproduction.

The process called **respiration** is the ability of these species to inhale oxygen and exhale carbon dioxide. This process occurs in their respiratory system. Hence, the correct answer is **C**

C

**Vertebrates** are animal species that are characterized and differentiated by having a backbone or vertebral column in their body. These organisms are under Phylum Chordata, meaning they possess a notochord, which is a vital component in vertebrate development. Hence, the correct answer is **A**

A

**Bilateral symmetry** is a type of body plan in which the body can be divided along the plane and into mirror images along a given central axis. The parts can be arranged on opposite sides–left, right, or top and bottom, Organisms exhibiting this type of symmetry have an anterior side, and posterior size, it also shows cephalization. Hence, the correct answer is **B**

B

In the early development of animal species, the blastopore’s fate leads to the central tube that transverse along the length of the developing embryo. This tube then formed the digestive tract and can be arranged in two ways: Deuterosome and protostome

**Deuterostome** is the animal species in which the blastopore forms the anus, It is also composed of three germ layers, outer ectoderm, middle mesoderm connected with the inner endoderm as shown in the figure. Hence, the correct answer is **C**

C

In the early development of animal species, the blastopore’s fate leads to the central tube that transverse along the length of the developing embryo. This tube then formed the digestive tract and can be arranged in two ways: **Deuterosome** and **protostome**.

**Protosome** is the animal species in which the blastopore forms the mouth, It is also composed of three germ layers, outer ectoderm, middle mesoderm lounging near to the inner layer called the endoderm,

The phylum Porifera means pore-bearing organisms. Since sponges are characterized by the presence of pores, they belong to the phylum Porifera.

C

**Cephalization** is one of the characteristics of many animal species, in which the sense organs and as well as nerve cells are concentrated towards the anterior side of the body. This allows the organism to process information received from its environment efficiently and it helped in the evolution of an effective digestive tract such as the position of the mouth in food processing. The correct answer is **B**

B

Cnidarians are radially symmetrical and they contain a mouth located at the center of the body. This is surrounded by many tentacles that can extend forward and outward of the organism’s body. They have two different forms in their life cycle– polyp or medusa.

**Polyp** has a cylindrical body with the mouth pointing upward, and these organisms are sessile, meaning they don’t move from one location to another and don’t have any locomotor organs. Hence, the correct answer is **A**

A

**Cnidarians** are radially symmetrical and they contain a mouth located at the center of the body. This is surrounded by many tentacles that can extend forward and outward of the organism’s body. They have two different forms in their life cycle– polyp or medusa.

Hence, the correct answer is **B**

B

**Animals** are heterotrophic species that function to carry various living processes including feeding, respiration or breathing, circulation, response to the environment, homeostasis, and reproduction. These organisms are eukaryotic multicellular, and they lack cell walls. They have high levels of specialization and internal organization which makes them a higher form of species.

**Epithelial cells** are cell types that line the various surfaces of our body. They are located in the vessels, skin, lungs, and other body organs. They cover the surfaces of these structures and they perform important functions including protection, secretion, filtration, and absorption.

**Epithelial cells** inside our lungs serve various important functions including filtration of the outside air as we inhale, barrier protection, fluid balance, and aid in the immune response by secreting mucus that traps foreign substances.

**Homeostasis** is the state of organisms being internally, physically, molecular, and chemically in balance. A way how an organism maintains homeostasis is through an *internal feedback mechanism*. **Internal feedback mechanism** can be either positive or negative.

A **positive feedback mechanism** pump or amplify the starting stimuli in those processes that need to be pushed for completion rather than maintenance. For example: childbirth. On the other hand, **negative feedback mechanism** counteract the changes in the given process and act to oppose the present stimulus that can trigger unnecessary process. For example: maintenance of body temperature.

Here are the sample drawings of a fish, jellyfish, and a sea sponge.

**Cephalization** is the concentration of sense organs and nerve cells towards the front of the body. This allows the animal to analyze more information about its environment, and it allowed an evolution to have an effective digestive organs such as the mouth for processing food sources.

The term protostome refers to the animals, which are mostly invertebrates, having a mouth that is formed by the blastophore. On the other hand, in deuterostomes, their oral end or anus is formed by the blastophore.

**Endoderm** is one of the primary germ layers composed of a various mass of cells found in the embryo of a vertebrate organism. It is located in the innermost portion and develops into the **gut** and other internal organs of the body.

**Mesoderm** is another primary germ layer that is found between the endoderm and the ectoderm. The fate of this germ layer is the formation of the muscles, bones, and blood vessels.

**Ectoderm** is the last and the outermost germ layer and it later forms the skin, sweat glands, other receptors found in the integumentary system, and the lining of the body cavity.

**Sponges** especially those *harder sponges* are composed of spiny spicules that act as their skeleton. These *spicules* are spike-shaped chalk-like structures made up of calcium carbonate or glass-like silica.

**Archaeocytes** are the cells that make up these spicules. They are specialized cells that transverse around the walls of the sponge organism.

Sponges are feeding themselves with the help of choanocytes in the body cavity that engulf the water and food particles. In turn, the food is digested by the archaeocytes.

Sponges exhibit respiration and excretion by the movement of water through their bodies. They dissolved oxygen from the water is diffused into the cells during respiration. On the other hand, wastes are expelled together with the water that is carried away by the sponges.

**Sponges** play an important function in aquatic ecology. Sponges give habitat to marine animals like sea stars and shrimp which establish a commensal relationship between them. Another symbiotic relationship is between sponges and photosynthetic algae. These photosynthetic organisms provide food and oxygen to the sponges and in return, the sponges provide shelter and protection to these species (mutualistic relationship).

**Statocysts** are balance receptors found in aquatic invertebrates that help these species to have their proper balance and orientation. These receptors help the organism to maintain equilibrium such as rising to the surface of the water environment or sinking in it.

The diet of cnidarians includes small crustaceans. They are carnivorous in nature and they capture their prey by discharging nematocysts to paralyze them. Once they are able to push the food into their gastrovascular cavity, the digestion will start. This takes places outside the cells first, then the remaining partially digested food is absorbed by the gastroderm. On the other hand, the undigested food particles are expelled through their mouth, while the waste is diffused through their body walls.

**Polyp** reproduce asexually through the process of budding. One type of budding process happens when the side of the existing polyp begins to swell, and this swelling will then grow and produce a new polyp that has identical genetic information to that of the parent polyp. Another way is to produce tiny medusas that separate and become a new individual polyp.

Aurelias undergo sexual reproduction to reproduce offspring. First, gametes are released in the water. Once the gametes fuse, fertilization will take place. The zygote formed by fertilization will grow into a ciliated larva. Then, the swimming larva attaches to a hard surface and later on develops into a polyp. In turn, the polyps go through budding to produce a medusa. Once the medusas mature, the cycle starts again.

Sponges which belong to phylum Ponfera are similar to other animals as they are multi cellular, heterotrophic, have no cell walls and carry out basic functions such as feeding, respiration, excretion, response and reproduction. They also have some specialized cells. Sponges are different from other animals in few characters. As the name of the phylum Ponfera suggests they are pore – bearers. They have pores all over the body. They are sessile. They can reproduce either sexually or asexually.

Here are the different questions that can be used to study gemmules:

A. How are gemmules produced? How can they help the sponges in sponge reproduction?

B. Can gemmules survive without an oxygen supply?

C. How are gemmules resistant to dehydration and freezing temperature?

Cnidarians have long tentacles that are outstretched from their body. These tentacles entrap the fish and paralyze them. Therefore cnidarians do not go toward their prey.

Human activities like recreational divers damage the coral reefs. This happens accidentally in most cases. This activity destroys the coral reefs which in turn disturb the home for some green algae If human can control their recreation activities and restrict them to the beaches only then the coral reefs can be prevented from any damage.

The life cycle of a cnidarian is more complex than sponges. Cnidarians undergo sexual and asexual reproduction. It goes through external fertilization and there is a transition that happens between a polyp and a medusa. Aside from that, unlike sponges, cnidarians have complex structures and organs. In sponges, they reproduce sexually through internal fertilization and asexually by budding or by gemmules.

The nerve net, which is considered as the cnidarian nervous system, triggers the cnidocytes to release a poisonous substance that paralyzes a prey. The nerve net is usually distributed around the body of a cnidarian but most of these are found around its tentacles. This is the reason why a cnidarian releases poison when a foreign object touches its tentacles.

The internal feedback mechanism of the body tells what it needs in order to maintain homeostasis. Similar to the job of an inventory clerk, it tells what needs should be restocked, whether it is food, nutrient, or oxygen supply, in order for it to run its normal operations or processes.

Sponges carry out functions by the movement of the water inside and out of their bodies. Choanocytes, with the use of their flagella, help the current of the water to move inside the pores of the sponge. Because of these specialized cells, functions like feeding, respiration, circulation, and excretion were carried out by the sponges.

The Portuguese man of war is not a single organism, it is actually a colony of individuals, which are closely related to jellyfishes, that perform different functions. They are similar to hydras which have polyps that grow in colonies. However, the difference between hydras and Portuguese man of war lies in terms of the presence of the medusa stage. Hydras lack a medusa stage, while the Portuguese man of war consists of medusas and polyps.