Question

Which of the following characteristics is/are true about arthropods?
A. Unisexual with sexual dimorphism
B. Metamorphosis in their life cycle
C. Fertilization is usually internal but in some, it may be external.
D. All of the above

Answer 1

Arthropoda means “jointed legs”. The body of arthropods is segmented.

Complete answer: Arthropods have a hard exoskeleton made of chitin, which gives them physical protection and resistance to drying out.
In order to grow, arthropods shed this outer covering in a process called molting.
They are mostly unisexual and exhibit sexual dimorphism but some are hermaphrodites.
Arthropods belonging to the class Insecta show metamorphosis in their life cycle.
In terrestrial arthropods, fertilization is internal but aquatic arthropods show internal as well as external fertilization

Additional information: Arthropods has a segmented body with a head, a thorax, and abdomen segments.
1. They can be used for feeding, sensory reception, defense, and locomotion.
In addition to legs, antennas and mouthparts are considered modified appendages.
2. An open circulatory system with hemolymph, a blood-like fluid.
A series of hearts move the hemolymph into the body cavity where it comes in direct contact with the tissues. Hemolymph is involved with oxygen distribution.
3. They have a complete digestive system with a mouth and an anus.
4. Aquatic arthropods use gills to exchange gases. These gills have a large surface area in contact with the water, so they can absorb more oxygen.
Land-living arthropods have internal surfaces that help exchange gasses.
5. Insects and most other terrestrial species have a tracheal system, where air sacs lead into the body from pores in the exoskeleton. These pores cover a large part of their external body surface.
6. Others use book lungs, gills modified for breathing air, as seen in species like the coconut crab.

So, the answer is D. All of the above

Note: Arthropoda has four living subphyla-
1. Chelicerata, which includes spiders, mites, and scorpions.
2. Myriapoda includes centipedes and millipedes.
3. Hexapoda includes insects.
4. Crustacea, which includes lobsters, crabs, barnacles, crayfish, and shrimp.