Question

Alary muscles in cockroach are associated or connected with
A. Trachea
B. Heart
C. Legs
D. Alimentary canal

Answer 1

The heart of the cockroach is myogenic that means the rhythmic contractions which take place in the heart are due to muscles and not due to any neural regulation. Cockroach possesses an open type of blood circulation.

Complete answer:
The scientific name of cockroach is Periplaneta americana. These come under the members of phylum Arthropoda in which they are placed in class Insecta. They act as serious pests as well as vectors for several diseases. Cockroaches have an open circulatory system, therefore their blood vessels are poorly developed which open into haemocoel. Haemocoel is a true coelom just like other coelomic animals. The blood in the cockroach is called hemolymph which is composed of colourless plasma and haemocytes. Visceral organs present in the haemocoel are directly bathed in the haemolymph. The heart of the cockroach is 13 chambered which lies along the mid-dorsal line of thorax and abdomen. It appears like an elongated muscular tube. Each chamber is funnel-shaped which has ostia on either side. Blood from body cavities or sinuses enters the heart chambers with the help of ostia and then it is pumped to sinuses again anteriorly. A pair of alary muscles are attached to the walls of each heart chamber. Alary muscles are triangular muscles that appear like fans. There are 12 pairs of alary muscles attached to the dorsal diaphragm and laterally to heart chambers. The pointed ends at the outer side are connected to the terga. The muscular wall of the heart creates pulsations which are assisted by alary muscles. Out of 13 chambers of the heart, 3 chambers are thoracic and 10 chambers lie in the abdomen, hence the remaining are abdominal.
Hence, the correct answer is option C.

Note: There is no respiratory pigment present in the haemolymph of the cockroach, therefore it has no role in the transport of respiratory gases. Since most of the organs including the brain are present in the thorax and abdomen it can survive without head upto 7 days, without water upto 14 days, and without food for about one month.