Answer to Question #219925 in Zoology for Nani

Question

Instruction

✓Clear readable writing is recommended

✓The total number pages must be 6 or 7

✓submitted date 26-07-2021

#Q. Select three of the different phyla of invertbrates you learned and discuss in detail based on the following criteria.

√ Reproduction

√ symmetry

√ Respiration and Circulation

√ Nervous system

√ Digestion and excretion

Answer 1

Porifera

Sponges reproduce asexually as well as sexually. The majority of sexually reproducing poriferans are hermaphroditic, which means they produce eggs and sperm at different times. Often, sperm is "broadcast" into the water column.

Asymmetry. Only members of the phylum Porifera (sponges) have asymmetrical body plans. As adults, certain fish species, such as flounder, lack symmetry. The larval fish, on the other hand, are bilaterally symmetrical.

Sponges are aquatic animals with small holes in their bodies known as Ostia. The Ostia enable water, oxygen, and other nutrients to enter the sponge's body while also allowing waste products like ammonia and carbon dioxide to leave. A sponge's respiratory system is based on the diffusion process.

Sponges, unlike other creatures, lack a nervous system and organs. They lack eyes, hearing, and the capacity to feel anything physically. They do, however, contain specialized cells that perform various tasks inside their body.

Their digestive system comprises a series of incurrent tubes that enable water to flow into the poriferan's core chamber. Choanocytes catch plankton-like food in their collars when water rushes in. Any metabolic waste products exit via the osculum, a central aperture at the top of the poriferan.

Cnidaria

 Medusae reproduce most of the time sexually. A zygote is formed during sexual reproduction. The zygote grows into a larva known as a planula. The planula then grows into a polyp.

Cnidaria's bilateral symmetry is believed to have been inherited from the progenitors of both cnidarians and triploblastic bilaterians. Cnidaria's secondary radial symmetry is clearly a consequence of adaptation to the sessile way of life.

Cnidarians are aquatic creatures with stinging cells known as cnidocytes. Respiratory systems are the bodily systems that take in required gases and expel waste gases. Although cnidarians lack lungs and other respiratory systems, they utilize body cells to absorb oxygen and discharge waste gases.

The fundamental design of the cnidarian nervous system is that of a nerve net that has condensed to create nerve plexuses or circular or longitudinal nerve tracts that may be syncytia in some places.

Food is absorbed via the mouth and then transferred through the coelenteron, a major digestive area. Any food that cannot be digested is ejected back via the animal's mouth. So, indeed, the mouth and anus of a cnidarian are basically the same bodily part.

Platyhelminthes

Flatworms are hermaphroditic (they have both male and female sex organs) and may reproduce both sexually and asexually. Cross-fertilization accounts for the vast majority of sexual reproduction (where both individuals fertilize each other).

The bodies of flatworms are bilaterally symmetrical, with a distinct head and tail area. They have a central neurological system, which includes a brain and nerve cord. Eyespots are clusters of light-sensitive cells on each side of their heads.

Flatworms do not have a respiratory or circulatory system; these activities are accomplished via absorption through the body wall. Nonparasitic forms have a rudimentary, partial stomach; many parasitic organisms lack even this. Longitudinal, circular, and oblique muscle layers regulate movement in certain flatworms.

The phylum's flatworms Platyhelminthes have a central nervous system (CNS) that consists of a tiny "brain" and two nerve cords, as well as a peripheral nervous system (PNS) that consists of a network of nerves that extends throughout the body. The nervous system of insects is more sophisticated but also very dispersed.

Most flatworms ingest food via their mouths and then transport it to a digestive gut that connects to the digestive structures. The meal is subsequently broken down and absorbed by the remainder of the body. Some have an anus to eliminate wastes, but the vast majority do not and will excrete unwanted food via the mouth.