Holothuria atra and Actinopyga echinites (Massin and Doumen 1986). Holothuria
theeli ranged in size from \5 to 20 cm in length. The relative absence of juveniles
(individuals less than 5 cm in length) and distinct cohorts upon the midshelf reef
suggest different habitat preferences between juveniles and adults (5–11 and
11–20 cm long, respectively). This probably also occurs with the population of
Isostichopus fuscus in the Galápagos Islands (Martínez et al. 1998), and with
H. atra and S. chloronotus from the Great Barrier Reef (Uthicke 2001). Small and
medium juveniles inhabit areas with boulders, cobbles, pebbles and sand, whereas
large adults mainly inhabit areas with boulders and cobbles. In order of preference
the most used microhabitats were boulders/cobbles [ pebbles/sand [ thick
pavement/bedrock (Sonnenholzner and Lawrence 2002).
Growth and Reproduction
Sonnenholzner (2003) determined abundances of H. theeli on transects on a
shallow tidal reef flat at the Puntilla Santa Elena (Fig. 6.1) in 1994. Abundances
were variable in May but increased by the end of August as a result of asexual
reproduction by fission (during the sampling period many individuals were
observed without a mouth and none without an anus). The fluctuation in abundance following the period of fission could be related to the survival rates for
posterior and anterior body parts (Reichenbach and Holloway 1995). The importance of fission in reproduction is a well-known feature in the biology of this
species (Bonham and Held 1963; Uthicke 1997). Many individuals were observed
regenerating after asexual reproduction in May. The fission rate of individuals in
the intertidal zone to near shore reef was much higher (15–36 %) than at the highenergy midshelf reef zone (3–7 %) (Sonnenholzner 2003).
Diet and Feeding Habits
Sonnenholzner (2003) determined that the distribution pattern of H. theeli on a
shallow tidal reef flat was apparently not limited by food availability (Yamanouchi
1956). Roberts (1979) and Pomory et al. (1998) suggested differences in feeding
time as a means of niche partitioning, where the habitat was partitioned into
microhabitats to avoid competition with other holothurians species found in the
area. Holothuria theeli generally begins burrowing around sunrise and emerges
close to sunset, showing a semi-cryptic behavior at night. Sonnenholzner (2003)
determined that the feeding activity of H. theeli may be low in May compared to
March and August, since the intestine length was shorter in May, the capacity of
the intestine may fluctuate as a physiological response to food availability (Tanaka
1958). For example, Stichopus japonicus ceases feeding after spawning and its
intestines degenerate and become smaller in size (Tanaka 1958). The dormant
condition in H. theeli may result from the change in water temperature from high
to low, which may stimulate physiological processes such as feeding inactivity
after spawning (Yamanouchi 1942). Under these conditions, H. theeli maintains
6 Echinoderms of Ecuador
199
theeli ranged in size from \5 to 20 cm in length. The relative absence of juveniles
(individuals less than 5 cm in length) and distinct cohorts upon the midshelf reef
suggest different habitat preferences between juveniles and adults (5–11 and
11–20 cm long, respectively). This probably also occurs with the population of
Isostichopus fuscus in the Galápagos Islands (Martínez et al. 1998), and with
H. atra and S. chloronotus from the Great Barrier Reef (Uthicke 2001). Small and
medium juveniles inhabit areas with boulders, cobbles, pebbles and sand, whereas
large adults mainly inhabit areas with boulders and cobbles. In order of preference
the most used microhabitats were boulders/cobbles [ pebbles/sand [ thick
pavement/bedrock (Sonnenholzner and Lawrence 2002).
Growth and Reproduction
Sonnenholzner (2003) determined abundances of H. theeli on transects on a
shallow tidal reef flat at the Puntilla Santa Elena (Fig. 6.1) in 1994. Abundances
were variable in May but increased by the end of August as a result of asexual
reproduction by fission (during the sampling period many individuals were
observed without a mouth and none without an anus). The fluctuation in abundance following the period of fission could be related to the survival rates for
posterior and anterior body parts (Reichenbach and Holloway 1995). The importance of fission in reproduction is a well-known feature in the biology of this
species (Bonham and Held 1963; Uthicke 1997). Many individuals were observed
regenerating after asexual reproduction in May. The fission rate of individuals in
the intertidal zone to near shore reef was much higher (15–36 %) than at the highenergy midshelf reef zone (3–7 %) (Sonnenholzner 2003).
Diet and Feeding Habits
Sonnenholzner (2003) determined that the distribution pattern of H. theeli on a
shallow tidal reef flat was apparently not limited by food availability (Yamanouchi
1956). Roberts (1979) and Pomory et al. (1998) suggested differences in feeding
time as a means of niche partitioning, where the habitat was partitioned into
microhabitats to avoid competition with other holothurians species found in the
area. Holothuria theeli generally begins burrowing around sunrise and emerges
close to sunset, showing a semi-cryptic behavior at night. Sonnenholzner (2003)
determined that the feeding activity of H. theeli may be low in May compared to
March and August, since the intestine length was shorter in May, the capacity of
the intestine may fluctuate as a physiological response to food availability (Tanaka
1958). For example, Stichopus japonicus ceases feeding after spawning and its
intestines degenerate and become smaller in size (Tanaka 1958). The dormant
condition in H. theeli may result from the change in water temperature from high
to low, which may stimulate physiological processes such as feeding inactivity
after spawning (Yamanouchi 1942). Under these conditions, H. theeli maintains
6 Echinoderms of Ecuador
199