Pilumnus sayi

are eaten by

• Global Biotic Interactions: Loligo plei
• Global Biotic Interactions: Pareques acuminatus (Bloch & Schneider 1801) (Highhat)
• Global Biotic Interactions: Pareques acuminatus (Bloch & Schneider 1801) (Highhat)
• Global Biotic Interactions: Ginglymostoma cirratum (Bonnaterre 1788) (Nurse Shark)
• Global Biotic Interactions: Halichoeres caudalis (Poey 1860) (Painted Wrasse)

are preyed upon by

• Global Biotic Interactions: Epinephelus morio (Valenciennes 1828) (Red Grouper)

eat

• Global Biotic Interactions: Siphonodictyon brevitubulatum Pang 1973 (short-tubed boring sponge)
• Global Biotic Interactions: Verongula gigantea (Hyatt 1875)
• Global Biotic Interactions: Hyrtios violaceus (Duchassaing & Michelotti 1864)
• Global Biotic Interactions: Cliona varians (Duchassaing & Michelotti 1864)
• Global Biotic Interactions: Verongula rigida (Esper 1794)