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- A huge clam that was on the verge of extinction has made a comeback, with a surge in numbers in waters off Croatia, marine biologists say. The clam, is known as the noble pen shell or pinna nobilis.
- Pinna nobilis, whose common name is the noble pen shell or fan mussel, is a large species of Mediterranean clam, a marine bivalve mollusc in the family Pinnidae, the pen shells.
- It reaches up to 120 cm of shell length. It produces a rare manganese-containing porphyrin protein known as pinnaglobin.
- The bivalve shell is usually 30–50 cm long, but can reach 120 cm.
- Its shape differs depending on the region it inhabits. Like all pen shells, it is relatively fragile to pollution and shell damage.
- It attaches itself to rocks using a strong byssus composed of many silk-like threads which used to be made into cloth.
- The animal secretes these fibres from its byssus gland; they consist of keratin and other proteins and may be as long as 6 cm.
- The inside of the shell is lined with brilliant mother-of-pearl.
- As with other members of its genus, Pinna nobilis hosts symbiotic shrimp which live inside its shell.
- is believed that when it sees a threat, the shrimp warns the host, perhaps by retracting its claws or even by pinching.
- The clam then closes shut. It has been demonstrated that the shrimp has a similar filter-feeding diet to its host and the relationship is likely mutualistic.
- This species is endemic to the Mediterranean Sea, where it lives offshore at depths ranging between 0.5 and 60 m.
- It could be found buried beneath soft-sediment areas (fine sand, mud, often anoxic).
- In December 2019, Pinna nobilis has entered the IUCN Red List as critically endangered.
Q. Consider the following statements:
1. Pinna nobilis has entered the IUCN Red List as critically endangered.
2. Pinna nobilis hosts symbiotic shrimp which live inside its shell.
3. Pinna nobilis species is endemic to the Mediterranean Sea.
Which of the above statements is/are correct?
A) 1 and 3 only
B) 2 only
C) 3 only
Answer: D) All