BATHYMETRIC PATTERNS OF BODY SIZE IN DEEP-SEA GASTROPODS

Area of Science:

• Marine Biology
• Deep-Sea Ecology
• Evolutionary Biology

Background:

• Global biogeographic patterns of marine invertebrate size at the deep-sea threshold are not well understood.
• Size-depth clines within deep-sea ecosystems are poorly understood phenomena.

Purpose of the Study:

• To present the first standardized measurements of larval and adult size in deep-sea gastropods (Turridae) across a broad depth range.
• To investigate size-depth clines in a major deep-sea family.

Main Methods:

• Standardized measurements of larval and adult size were taken.
• Data were collected from ecologically and phylogenetically similar species.
• A broad and continuous depth range, from the upper bathyal to the abyssal plain, was studied.

Main Results:

• Size at all life stages significantly increases with depth.
• Consistent size-depth clines were observed across the studied gastropod family.
• Larger body size was favored at greater depths.

Conclusions:

• Selection may favor larger body size at greater depths due to metabolic and competitive advantages.
• The generally small size of deep-sea mollusks might be an independent evolutionary process favoring invasion by small inshore taxa.