Question

The blood pigment of earthworms is

• A. Haemocyanin
• B. Haematin
• C. Cyanin
• D. Haemoglobin

Answer 1

Answer: (D)

Haemoglobin

• The blood system of annelids is a closed system, meaning that they have blood vessels through which the blood flows. There are two main longitudinal blood vessels, a dorsal one and a ventral one, as well as three smaller longitudinal vessels, two lateral neural vessels, and one sub-neural vessel.
• These vessels have circular muscles around them which can contract rhythmically to keep the blood moving around the body.
• The vessels also contain valves that ensure the blood only flows in one direction. Blood flows from the head to the tail in the ventral vessel and back, from the tail to the head, in the dorsal vessel. In each segment, a number of smaller lateral (side) vessels branch off from the main vessels to supply the sections of that segment.
• The blood of annelids contains hemoglobin, the same respiratory pigment as in humans, it is this that makes their blood the same red colour as ours.