Samantha Silvestri and Allie Gale

Samantha Silvestri and Allie
Gale 

The Effect of Diet
on Ink Response and Replenishment in
Aplysia
dactylomela

When threatened, the spotted sea hare
A. dactlyomela will release a deep purple ink as a defense
mechanism to deter predators. Each individual only has a limited
amount of ink in its ink gland, which it releases in rationed
portions each time it inks. Previous studies suggest that it takes
approximately two days for A. dactylomela to replenish its
ink reserves after completely depleting its supply. Our study tested
two groups of four sea hares each: a control group that was fed 205g
of the red algae Gelidiella acerosa daily and an experimental
limited-diet group that was fed 50g daily. Our experiment aimed to
see if there was a relationship between a restricted diet and ink
response time to a fabricated threat, as well as to test how quickly
A. dactylomela can replenish its ink reserves after inking.
We hypothesized that the sea hares that consumed a limited diet would
take a longer time to replenish their ink reserves and would not be
able to ink as frequently as those in the control group. We tested
our hypothesis by picking up and lightly jostling each sea hare for
up to one minute until it inked. This process was repeated every two
minutes for eight minutes, and the procedure was conducted every
twelve hours over the course of seven days. We found that the average
ink response time for each sea hare increased over the course of
eight minutes, and the number of inking events significantly
decreased in both groups throughout the eight minute trial. The
limited diet group on average stopped releasing ink earlier in each
trial than the control group. Our study supports the claim that sea
hares that consume a limited diet have a reduced inking frequency and
increased ink response time, though further research is required to
determine whether this is due to habituation or complete depletion of
ink.

 
Inking

Aplysia dactylomela releasing
ink during a trial

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