In today's lab we will explore the diversity of the invertebrate Phylum Mollusca (Latin for soft body). There are approximately 110,000 extant species of molluscs. These are found mainly in the marine environment with ample representatives in freshwater and terrestrial biomes.

Molluscs vary in size from tiny clams 0.5 millimeters in diameter to giant squids that reach 18 meters in length and do battle with sperm whales. However 80% of the molluscs are less than 5 centimeters in maximum shell size.

The phenomenon of adaptive radiation is seen again and again in evolutionary. The general idea is that some group of organisms evolve an innovative and highly successful adaptation or suite of adaptations that gives them tremendous advantage over contemporary competing groups. This temporary release from competition gives the adapted group the liberty to increase their numbers greatly which allows them to increase their variability and experiment with new genotypes. These novel organisms can potentially "radiate" or find their way into open niches available in the habitat or into entirely new environments and evolve into new species. You have already seen examples of this in the plant kingdom with the waves of adaptive radiation that occurred in the gymnosperms and later, on a much greater scale, in the angiosperms.