Question

Haemocyanin is found in-
a. Neries
b. Leech
c. Earthworm
d. Prawn

Answer 1

Hint: Hemocyanin is a protein which helps in transport of oxygen throughout the bodies of some organisms. Unlike the presence of hemoglobin in red blood cells, found in vertebrates, hemocyanins are proteins which are freely suspended in the hemolymph and are not bound to any blood cells. Oxygenation of Cu present in this protein results in formation of blue color.

Complete answer:
• Hemocyanins are proteins which contain copper and are responsible for the transport of oxygen in the blood plasma of arthropods (many crustaceans, some arachnids, and the horseshoe crab, Limulus) and molluscs (some bivalves, many gastropods, and cephalopods).
• When copper, present in the protein, gets oxidized due to oxygen, its state changes from first to second state. This oxidation state change is responsible for the color change of copper from colorless to blue color.
• Hemocyanins are found mainly in Mollusca and Arthropoda. This protein is also commonly found in cephalopods and crustaceans.
• The respiratory function of hemocyanin is very similar to hemoglobin but there are some structure differences between the both molecules.
• While hemoglobin carry only four oxygen molecules at a time, hemocyanin is known to carry about ninety-six oxygen molecules at one time.
• Also, hemoglobin being much smaller in size as compared to hemocyanin, millions of hemoglobin bind with each other inside the red blood cells; the latter is suspended freely in the hemolymph of arthropods and molluscs.
• Neeris is a genus of polychaete worms in the family Neritidae. Neeris worms are commonly known as rag worms or calm worms. They usually feed on small animals such as crustaceans, molluscs, sponges and other animals.
• Leeches are segmented parasitic worms belonging to Annelida phylum. The leeches’ body has thirty- two segments, each segment has its own brain and hence, leeches have thirty- two brains. They leech on the blood of frogs, fish, lizards, birds or even humans so as to survive and reproduce.
• Earthworm is an invertebrate that belongs to the order Opisthopora. They are externally segmented with respective internal segmentation, accompanied by setae on all segments.
• Some of the species are edible. Most of the prawns are free living aquatic species while some can be terrestrial or parasitic. They have an open circulatory system and contain hemocyanin making their blood appear Blue in color.

Hence, the correct answer is option (D).

Note: Animals like snails, octopus, and spiders have another molecule called hemocyanin to transport the oxygen inside their blood. Unlike hemoglobin, this pigment absorbs all colors and reflects blue color (due to the oxidation of copper in the molecule) and hence their blood appears to be blue. While for the organisms with no blood color (white), they do not carry oxygen through the bloodstream and their blood does not consist of an oxygen- carrying protein.