<p>Murex ternispina Lamarck, 1822 - black-spined murex snail shell, modern (latest Holocene) (abapertural view) (~9.6 centimeters tall)
</p><p>This species is also known as Murex nigrispinosus.
</p><p>The gastropods (snails &amp; slugs) are a group of molluscs that occupy marine, freshwater, and terrestrial environments.  Most gastropods have a calcareous external shell (the snails).  Some lack a shell completely, or have reduced internal shells (the slugs &amp; sea slugs &amp; pteropods).  Most members of the Gastropoda are marine.  Most marine snails are herbivores (algae grazers) or predators/carnivores.
</p><p>Seen here is a muricid gastropod with a spinose shell.  The high degree of spinosity is usually considered an anti-predation feature.  Spinose muricids typically have three axially-oriented rows of spines per whorl, so that each spine row is ~120º from the next.  Conchologists have pointed out that such spine row distributions provide orientation stability to the snail and prevent sinking on unconsolidated, fine-grained, high-water-content sediment substrates.  Another suggestion holds that well-developed spine arrays could act as traps for potential prey.  Muricids are predatory gastropods.  They principally prey on encrusting, conchiferous organisms (e.g., bivalves, barnacles) by boring through the shells.  It's likely that the spine arrays protect the snail from predatory arthropods or fish while engaged in boring &amp; feeding on prey.
</p>
Classification: Animalia, Mollusca, Gastropoda, Neogastropoda, Muricoidea, Muricidae
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/47445767@N05">James St. John</a>
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/jsjgeology/49624887263/">Murex ternispina (black-spined murex snail) 1</a>