Number of chambers in heart of cockroach is

✅ Explanation: The heart of a cockroach is a long, tubular structure located dorsally in the abdomen. It is divided into 13 chambers, each with a pair of ostia (openings) that allow hemolymph (insect blood) to enter.
Key Points
-Cockroaches have multi-chambered hearts that are shaped like tubes which are much more resistant to failure than human hearts.
-But instead of shaping the heart as a tube, they've created the chambers in a series of concentric spheres like an onion.
-A cockroach belongs to the class Insecta of phylum Arthropoda.
-They are brown or black-bodied animals.
-The size ranges from 0.6-7.6 cm and consists of a long antenna, legs, and flat extension of the upper body wall that conceals the head.

✏️The body of the cockroach is segmented and divisible into three distinct regions:
-Head
-Thorax
-Abdomen
-The whole body of the cockroach is covered by the hard chitinous exoskeleton which is brown in color.
-The circulatory system of cockroaches is an open type. Blood vessels in cockroaches are poorly developed and they open up into space known as hemocoel.
-The heart of the cockroach consists of an elongated muscular tube lying along the dorsal line of the thorax and abdomen.
-It is transformed into funnel-shaped chambers with Ostia. The cockroach has a 13 chambered tubular heart. Hence, Option 2 is correct.
-Oxygenated blood enters each chamber through a pair of slit-like openings known as Ostia.
-The first chamber opens into the aorta which further opens into head sinuses.
​Additional Information
-The heart is the key organ for blood circulation and double circulation is an efficient way of circulation as it provides an effective way of circulation.  
-Double circulation follows the main pathways, one for oxygenated blood and another for deoxygenated blood.
-The majority of mammals, including humans, utilize a double circulatory system. Double circulation includes systemic circulation and pulmonary circulation.