Question

1. Identify a unique characteristic that can be used to differentiate an organism from phylum Arthropoda from one in phylum Echinodermata. Identify an organism that is a arthropod, and one that is a echinoderm.

2. Distinguish between the process of molting and pupation

3.What are bilaterally symmetrical animals? Differentiate between pseudocoelomates and coelomates with regards how the germ layers are arranged. Then, identify a phylum of organisms considered an pseudocoelomate, and one that is a coelomate

4.Identify a unique characteristic that can be used to differentiate an organism from phylum Arthropoda from one in phylum Echinodermata. Identify an organism that is a arthropod, and one that is a echinoderm.

Answer 1

Ans-1) Unique character that can be used to differentiate an organism from phylum Arthropoda from one in phylum Echinodermata is symmetry.

Arthropods are bilaterally symmetrical, whereas in Echinoderms, adults are radially symmetrical and larvae are bilaterally symmetrical.

Arthropods can be identified by the presence of following characteristics:-

1. Symmetry - Bilateral symmetry.

2. Circulation - Blood vascular system (open type).

3. Respiration - By general body surface, gills, trachea or book lungs.

4. Digestive system - Complete digestive system.

5. Excretion - Malpighian tubules, Green's gland, Coxal gland.

6. Nervous system - Well developed, made up of nerve rings, is central and have solid nerve cord.

7. Fertilisation - Mostly dioecious and fertilisation is internal.

8. Habitat - Present in both land and water.

9. Have segmented body. 3 main body parts - head, thorax and abdomen

10. Have jointed appendages.

11. Have exoskeleton made up of protein and chitin.

Example - Spider, Scorpion, mites, ticks, insects

Echinoderms can be identified by the presence of following characteristics:-

1. Symmetry - Adults - radially symmetry

Larvae - bilateral symmetry.

2. Circulation - Water vascular system (open type).

3. Respiration - Dermal bronchiae, tube feet, respiratory tree or bursae.

4. Digestive system - Complete digestive system.

5. Excretion - Specialised excretory system absent.

6. Nervous system - Simple nervous system. Brain is absent, nerve rings are present around the mouth.

7. Fertilisation - Sexual dimorphism absent, external fertilisation with indirect development.

8. Habitat - Marine only.

9. Have endoskeleton.

Example - Starfish, sea urchin, sand dollar, sea cucumber.

Ans-2). Difference between Molting and Pupation.

Molting

Moulting or Molting, also known as sloughing, shedding, or in many invertebrates, ecdysis, is the process in which an animal routinely casts off its body part, either at specific times of the year, or at specific points in its life cycle.

Moulting can involve shedding of the epidermis (skin), pelage (hair, feathers, fur, wool), or other external layer. In some groups, other body parts may be shed, for example, wings in some insects or the entire exoskeleton in arthropods.

Pupation

It is the process of formation of Pupa.

A pupa is the life stage of some insects undergoing transformation between immature and mature stages. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, with four life stages: egg, larva, pupa, and imago.

Ans-3). Bilaterally symmetrical animals are those animals, whose body is bilaterally symmetrical, that is the property of being divisible into symmetrical halves on either side of a unique plane.

With regards to the arrangement of germ layers, pseudocoelomates and coelomates can be distinguished by :-

Pseudocoelom (false coelom) is derived from blastocoel, therefore also known as blastocoelom.

True Coelom is derived from mesoderm.

Pseudocoelomates can be identified by the following characteristics:-

1. Circulation - Opened circulatory system (consisting of body fluid, known as haemolymph).

2. Coelomic cavity is derived from blastocoel

3. Coelomic cavity is not lined by peritoneum.

Example - Rotifers, flat worms.

Coelomates can be identified by the following characteristics:-

1. Circulation - Closed circulatory system ( consisting of blood).

2. Coelomic cavity delivered from mesoderm.

3. Coelomic cavity lined by peritoneum.

Example - Annelids, Arthropods, Molluscs, Chordates.