Read the following statements carefully: A. Petromyzon is an ectoparasite on some fishes. B. Torpedo possesses a poison sting. C. Hippocampus is a marine cartilaginous fish. D. Salamandra has a heart with two auricles and one ventricle. How many of the above statements are correct?

Step-by-step solution

Statement A is correct. Petromyzon (Lamprey) belongs to the class Cyclostomata, whose living members are ectoparasites on some fishes. Statement B is incorrect. Torpedo possesses an electric organ, whereas Trygon possesses a poison sting. Statement C is incorrect. Hippocampus (Sea horse) is a marine bony fish belonging to the class Osteichthyes, not a cartilaginous fish. Statement D is correct. Salamandra is an amphibian, and amphibians have a three-chambered heart consisting of two auricles and one ventricle. Thus