Question

Identify the species? (Image of a shell with long, finger-like marginal projections)

• A. Lambis scorpius
• B. Murex tribulus
• C. Lambis crocata
• D. Lambis lambis

Hint:

Spider conchs (Genus Lambis) are easily identified by their "fingers".
1. Lambis lambis is the most common and has 7 fingers.
2. Lambis chiragra is huge and has fingers that look like heavy claws.
Always count the digitations for easier identification.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question asks to identify a gastropod species from an image of its shell. The shell has a distinctive appearance with long, spider-leg-like projections on the outer lip.
Detailed Explanation:

• Identification: The image depicts the "Common Spider Conch," which is scientifically known as Lambis lambis.

• Morphological Characteristics: Lambis lambis shells are large and heavy. The most striking feature is the presence of 6 to 7 long, curved, finger-like labial extensions (digitations). The siphonal canal is also elongated and curved. The interior of the aperture is usually smooth and can vary from white to pinkish-orange.

• Comparison with other options:
• Lambis scorpius (Scorpion spider conch) has more knotted, irregular digitations and a darker aperture.

• Lambis crocata (Orange spider conch) is smaller and typically has a bright orange aperture.

• Murex tribulus belongs to a different family (Muricidae) and is characterized by long, thin, straight spines, looking very different from the broad, curved "fingers" of Lambis.

• Habitat: These mollusks are common in the Indo-Pacific region, typically found in shallow coral reef areas and seagrass beds.

Step 2: Final Answer:
Based on the finger-like projections and general shell shape, the species is Lambis lambis.