Answer:
1 - Ecdysozoa
2 - Bilateria
3 - Annelida
4 - Parazoa
5 - Cnidaria
6 - Arthropoda
Explanation:
<u>1 - Ecdysozoa</u>
Species from the Ecdysozoa superphylum are characterized by the possession of an outer cuticle that is shedded through time as they grow. It is also the most diverse group of species of any other invertebrate group. It includes the phylum Nematoda (roundworms) and Phylum Arthropoda (arthropods).
These organisms also possess radial cleavage, are triploblastic - 3 embryonic cell layers: ectoderm, mesoderm, and endoderm.
2 - Bilateria
This group is comprised by animals who possess a bilateral symmetry, which means that their left and right sides are equal. Most organisms that possess bilateral symmetry are also triploblastic (explained above).
They are also characterized by having a head and a tail.
<u>3 - Annelida</u>
Organisms from this group are also known as "ringed worms" and are also very diverse and adapted to different environments. They are characterized by the possession of different segments throughout their body in which each segments has the same organs.
They are also triploblastic, display bilateral symmetry and have a spiral cleavage and schizocoelous coelom formation, which means that, during development, the cavity of the body is developed by the splitting of the mesoderm. Earthworms are examples of Annelida.
<u>4 - Parazoa</u>
Parazoans are mainly characterized by the absence of tissues. This groups includes organisms from the phyla Porifera and Placozoa. They are considered simple organisms as they only have three cell layers.
For instance, interestingly, sponge parazoans lack a circulatory system, respiratory system, digestive system, muscular system, or nervous system. Therefore, they are extremely simple but are highly adapted to their environment.
<u>5 - Cnidaria</u>
Cnidarians are very interesting organisms that are characterized by the possession of stinging cells known as cnidocytes that are used for predation and defense.
They exhibit two forms: swimming medusae and sessile polyps, which exhibit radiall symmetry and are diploblastic, which means they only possess ectoderm and endoderm, but no mesoderm. They possess a single cavity that is used for both respiration and digestion. Examples of cnidarians are jellyfish and corals.
<u>6 - Arthropoda</u>
This group includes insects, arachnids, myriapods, and crustaceans. They are characterized by having radial cleavage, bilateral symmetry, and segmented body parts, each with a pair of appendages.
Arthropods possess a rigid cuticle that cannot stretch so, as they grow, they moult and shed it so they can grow in size and get stronger as well. Some of them reproduce sexually while others can be hermaphroditic and reproduce asexually.
