Home to more species of plants and animals than any other state in the country, California is one of the world’s biodiversity hotspots.

The sea otters in Monterey Bay’s Elkhorn Slough estuary love to eat fat innkeeper worms. These marine worms construct burrows in the mud and extend the top end of their bodies to filter feed. The otters use their dextrous paws to grab the exposed portion of a worm, wipe away the sediment, and expose the protein-rich body inside.

Fat innkeeper worms (Urechis caupo) have hemoglobin cells in their body cavities, which is why they appear to spurt red blood when the otters squeeze them between their paws. Scientists think the hemoglobin helps the worms with oxygen storage during low tide periods.

A harbor seal pup rests on a bank at Elkhorn Slough.

The veins on a fallen leaf at Elkhorn Slough National Estuarine Reserve look almost like the branching arms of the estuary itself.