Mesostephanus appendiculatus

are eaten by

• Global Biotic Interactions: Leukoma staminea (Conrad 1837)
• Global Biotic Interactions: Rexithaerus secta (Conrad 1837)
• Global Biotic Interactions: Laevicardium substriatum (Conrad 1837)
• Global Biotic Interactions: Polydora nuchalis Woodwick 1953 (Polychaete)
• Global Biotic Interactions: Engraulis mordax Girard 1854 (Anchovy)

are parasitized by

• Global Biotic Interactions: Acanthotrema hancocki (Martin 1950) Lafuente, Roca & Carbonell 2000
• Global Biotic Interactions: Euhaplorchis californiensis
• Global Biotic Interactions: Phocitremoides ovale
• Global Biotic Interactions: Acanthoparyphium spinulosum
• Global Biotic Interactions: Parorchis acanthus (Nicoll)

are preyed upon by

• Global Biotic Interactions: Leukoma staminea (Conrad 1837)
• Global Biotic Interactions: Rexithaerus secta (Conrad 1837)
• Global Biotic Interactions: Polydora nuchalis Woodwick 1953 (Polychaete)
• Global Biotic Interactions: Nuttallia nuttallii (Conrad 1837) (California mahogany-clam)
• Global Biotic Interactions: Macoma nasuta (Conrad 1837)

have host

• Global Biotic Interactions: Felis catus Linnaeus 1758 (Domestic Cat)
• Global Biotic Interactions: Felis catus Linnaeus 1758 (Domestic Cat)
• Global Biotic Interactions: Felis catus Linnaeus 1758 (Domestic Cat)
• Global Biotic Interactions: Vulpes vulpes (Linnaeus 1758) (fox, red fox)

parasitize

• Global Biotic Interactions: Procyon lotor (Linnaeus 1758) (Northern Raccoon)
• Global Biotic Interactions: Nycticorax nycticorax (Linnaeus 1758) (Black-crowned Night Heron)
• Global Biotic Interactions: Numenius americanus Bechstein 1812 (Long-billed Curlew)
• Global Biotic Interactions: Syngnathus leptorhynchus Girard 1854 (Bay Pipefish)
• Global Biotic Interactions: Procyon lotor (Linnaeus 1758) (Northern Raccoon)