Question

Which of the following is commonly known as peanut worm?
A. Hirudo medicinalis
B. Sipunculus
C. Terebella
D. Polynoe

Answer 1

Peanut worms are pink smooth fat worms which are seen on the shores of the sea. They have the ability to shrink into a nut shaped ball to avoid predators. They are more commonly seen in mangroves and on soft ground. They are also found in sandy areas near seagrasses.

Complete answer:
Option A: Hirudo medicinalis is one among several species of leeches used as “medicinal leeches”. They’re commonly referred to as medical leeches.
So, option A isn’t correct.
Option B: These animals have the overall shape of shelled peanuts, which are commonly called peanut worms because when contracted, their ridged skins seem like the feel of peanut shells. Sipunculus is an unsegmented marine worm, which diverged from primitive annelid stock.
So, option B is correct.
Option C: Terebella may be a genus of polychaetes belonging to the Terebellidae. It has spaghetti tentacles on its head. Terebellids sleep in burrows or crevices and are often of huge size, ranging up to $150$ millimetres long and $15$ millimetres in breadth. The very long tentacles which radiate from near the mouth are used for locating and collecting food particles from the sediment surface.
So, option C isn’t correct.
Option D: Polynoidae are from the family of marine Polychaete worms which are commonly called scale worms.
So, option D isn’t correct.

Therefore, option B is the correct answer.

Note:
Peanut worms vary long from a couple of to $500$ millimetres ($1.6$ feet) or more long. These pink smooth fat worms are sometimes seen on a number of our shores. Though rare, they’ll be locally common on seabeds throughout the oceans of the planet. Peanut worms are bottom-dwelling (benthic) animals; most burrow within the mud or sand between tide levels or in oozes of the deepest ocean trenches.