All are features of non poisonous snakes except
**Core Concept**
Non-poisonous snakes, also known as non-venomous snakes, are characterized by their lack of venom glands and fangs. These snakes rely on constriction and other non-toxic methods to subdue their prey, and they do not possess the necessary anatomical structures to deliver venom.
**Why the Correct Answer is Right**
Non-poisonous snakes do not have a venom delivery system, which includes a pair of hollow fangs connected to a venom gland. This anatomical feature is characteristic of venomous snakes. Non-poisonous snakes, on the other hand, use their sharp, pointed teeth to grasp and hold onto their prey, but they do not inject venom. They also have a different head shape, with a more narrow, pointed snout compared to venomous snakes.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because non-poisonous snakes do have a pair of venom glands, which are typically smaller and less developed compared to venomous snakes.
**Option B:** This option is incorrect because non-poisonous snakes do have a pair of fangs, but they are not hollow and are not connected to a venom gland.
**Option C:** This option is incorrect because non-poisonous snakes do have a pair of venom glands, which are typically smaller and less developed compared to venomous snakes.
**Clinical Pearl / High-Yield Fact**
One key difference between non-poisonous and venomous snakes is the presence of a pit organ, which is a small depression on the head between the eye and the nostril. Venomous snakes, such as cobras, vipers, and rattlesnakes, have a pit organ that is highly sensitive to heat, allowing them to detect the body heat of their warm-blooded prey.
**Correct Answer:** D