Is predation of juvenile crown-of-thorns seastars (Acanthaster cf. solaris) by peppermint shrimp (Lysmata vittata) dependent on age, size, or diet?

Ten predation experiments were carried out examine whether predation of juvenile CoTS by peppermint shrimp (L. vittata) is affected by the age, size, or diet of juvenile CoTS.

Over a span of 9.5 months, ten experiments were carried out with juvenile CoTS ranging from 1 to 9 months of age and 0.34 mm and 21.37 mm in diameter. Juvenile CoTS were reared and fed a diet of either CCA throughout the experiments or corals (introduced at 4 months, and only offered from around 5 months ). Shrimps assessed for health status, measured with callipers to the nearest millimetre (from rostrum to tail) and left to acclimatize unfed in 250 ml jars for two–three days as suggested for invertebrate gut content analysis experiments, (5–16 per experimental run, depending on availability).

On the fourth day, a single juvenile CoTS was measured (maximum diameter, with callipers) and introduced into each jar. The jars were monitored daily for the following three days. The condition of the juvenile CoTs was scored as:

None – if there was not change in appearance

Partial predations – if they were alive but had missing limbs or injuries

Lethal predation – if they had been fully consumed by the predator.

Data analysis examined the effects of CoTS size and age on the incidence of partial and lethal predation.