Variation of Habitat for Echinaster sepositus
and Implications for Habitat Preference
Andreas Raisch
University of California Santa Cruz, Marine Biology
Abstract
Echinaster sepositus, commonly known as the Red Sea star, is a sea star located in the
Mediterranean Ocean. This species is usually over looked and as a result, under studied. This
study looks at the habitat usage as well as how depth and orientation affect the type of habitat
Echinaster associates with. Data was taken at STARESO Research Institute of Oceanography
while skin diving with the use of a quadrat. Multiple Echinaster specimens were spotted and
documented. It was discovered that Echinaster’s habitat does vary with depth and orientation.
Deeper stars were more commonly found to be associated with encrusting lavender coralline
algae and red sponge, while shallower stars were found to be more commonly associated with
turf and bushy algae. It was also discovered that Echinaster has a preference for certain species
such as turf algae, red sponge, and encrusting lavender coralline algae which were not incredibly
common in the environment regardless of depth. Posidonia oceanica was very prevalent in the
environment, but wasn’t commonly seen in association with Echinaster. Differences were also
seen between the two orientation types.
Introduction
The Mediterranean is famous for its clear waters and beautiful scenery as well as high
species composition (Danavaro et al., 2010). Various species of sea stars inhabit the
Mediterranean such as Echinaster sepositus, Ophidiaster ophidianus, and Coscinasterias
tenuispina (Deblius et al., 2003). In many environments, Asteroids (a class of sea star) are an
essential part of many benthic ecosystems as well as an important factor to maintaining the
environment (Hyman, 1955, Paine, 1966, Manzur et al., 2010). Many species of sea stars are
considered keystone species which can have huge potential impacts on the environment (Paine,
1969). The idea of a keystone species, first coined by Robert Paine in 1969, is a species that has
a much larger impact on the environment than its abundance (Paine, 1969). The idea of keystone
species has been deeply rooted in the work with sea stars, and often times, goes hand-in-hand
with habitat association. This leads into the development of a link between Echinaster and its
habitat.
As it is already known, in many environments, sea stars are known to be keystone species
and can have deleterious effects on the environment (Pain, 1969). A famous example is looking
at the sea star Pisaster ochraceus and its role as a key stone predator in the North Pacific (Paine,
1966). Many other sea stars have been researched as well such as Asterias vulgaris and
Leptasterias polaris (Himmelman and Dutil, 1991) with their feeding and population structure
examined. Oddly enough, despite being one of the more common sea stars in the Mediterranean,
Echinaster sepositus is under studied. One of the few studies on this specific species was run by
Villamor et al., (2010) in which the goal was to find out more about the spatial distribution of
Echinaster and what type of effect it has on shallow water communities as well as determining a
link between Echinaster and coralline algae. Echinaster is seen to either be very abundant or
almost empty in various parts of the Mediterranean (Villamor et al., 2010). This is thought to be
caused by either biotic or abiotic factors (Underwood and Chapman, 1996), but there isn’t
enough information to conclude this, which leaves the question open-ended (Villamor et al.,
2010). It is possible that Echinaster is a keystone species, but due to the limited knowledge, it
cannot be confirmed nor denied. It is my goal to help provide more substantial data about
Echinaster using the data I plan to collect on its association in and around STARESO.
The ultimate goal of this project is to further the understanding of the species Echinaster
sepositus. Leading off of the Villamor et al., (2010) study, where a relationship with Echinaster
and crustose coralline algae was noted. I hope to improve and expand on the relationship of
Echinaster with certain algal or invertebrate species and obtain a firm idea of its habitat
association and patterns. In order to achieve these results, Echinaster was observed in and around
STARESO harbor. Each individual star spotted was documented using a quadrat and a
categorical system to classify the habitat and substrate type (similar to Villamor et al., 2010).
I ask three questions in this experiment. First, does habitat usage vary with depth? The
specific hypothesis to go along with this is Echinaster found at deeper depths (> 21 ft) will have
different habitat than shallower depths (< 20 ft). Second, does Echinaster show a preference for a
specific habitat type? The specific hypothesis is Echinaster will show a preference for algae over
invertebrates. Lastly, does depth and orientation of Echinaster affect habitat cover preference?
The specific hypothesis is Echinaster found on vertical substrates will have different habitat than
stars found on horizontal substrates.
Materials and Methods
Species Description:
The species being observed is Echinaster sepositus (Retzius 1783). This species of sea
star belongs to the order Spinolusida, and the family Echinasteridae. Echinaster is a very
common sea star in the Mediterranean and is found ranging from the British Isles down to Cape
Verde off the coast of North West Africa, including the Mediterranean (Debelius et al., 2003).
The sea star is often seen in conjunction with various orange sponges (Crambe crambe, and
Scopalina lophyropoda) since it is believed that Echinaster is a predator (Garcia-Raso et al.,
1992, Maldonado et al., 1998). Echinaster ranges from 2-250 m in the water column (Debelius et
al., 2003). It is often seen on soft and hard substrates which include beds of Posidonia oceanica
(Debelius et al., 2003), as well as being more common in areas with higher amounts of stone like
objects (Entrambasaguas et al., 2008). Another sea star, Ophidiaster ophidianus, is in the same
geographical range as Echinaster and is often mistaken for Echinaster. One way to determine the
difference is that Echinaster is softer and has less rounded arms (Debelius et al., 2003). Contrary
to what has been said, it is also believed that Echinaster is not a predator and instead grazes on
the organic layer on the sea floor (Debelius et al., 2003). It has been noted that Echinaster has
also been seen feeding on various invertebrates, algae and sediment (Fergusen, 1969).
Site Description:
This experiment took place at STARESO Research Institute of Oceanography just
outside Calvi, Corsica. The observational data was taken from the harbor as well as the north and
south sides of the harbor. Data was taken from within 100 m on either side of the harbor (Fig. 1).
The sea stars were sampled at random (meaning every sea star seen was noted), and no
preference was shown when noting the habitat (habitat referring to the immediate surrounding
biotic and abiotic features and organisms defined by the quadrat) of the star (any sea star was
acceptable). There was very little wave action the majority of the time while at Stareso and rain
action was also quite minimal. The sites where the stars were picked-up varied from rocky beds
to fields of Posidonia, a common sea grass in the area. The substrate type didn’t vary much
between the inside of the harbor and either side of the harbor. The rocks were often covered in
multiple different algal and invertebrate species with turf and bushy algae being the dominant
organisms. The Posidonia also harbored various species of fish as well as invertebrates. The
species composition in the area was quite high. The stars were collected at various depths
between 3 ft to roughly 45 ft and the species composition was mostly consistent with depth
(Villamor et al., 2010). The north and south sides of the harbor were roughly the same regarding
species composition, but more stars were found along the northern side of the harbor.
Figure 1: The purple line denotes the sample area which includes the harbor, and surrounding areas
Methods:
Does habitat usage vary with depth?
Before any testing of the hypothesis was done, a survey of the area was completed, to
determine the abundance of Echinaster, as well as looking at their depth profile. Abundance and
depth were noted to see if I, a snorkeler, would be able to accomplish the various hypotheses.
Once these preliminaries were checked off, a quadrat was made using tubes, and string. The
quadrat was a normal nine point quadrat, meaning there are a total of nine points that are marked
on the inside of the quadrat.
In order to test the theory that habitat usage varies with depth, I went out with a partner
to either the harbor, or the north and south sides of STARESO and searched for sea stars in order
to document their habitat. The farthest documentation of a star occurred within 100 m on either
side of the harbor (Fig. 1). There was no preference shown for a star, and when one was noted,
no GPS data was taken on its location. Selection of stars was random in the sense that what was
seen was documented. First, it was noted what substrate type the sea star was on. The categories
ranged from boulders, cobble, cement, and jacks to beds of Posidonia. Second, the depth of the
sea star was taken using a depth gauge borrowed from one of the scuba divers. Third, the
orientation of the star on the substrate was taken. Fourth, one of the snorkelers dove down and
placed the quadrat over the sea star with the star lying on the middle point of the quadrat. Each
point was noted on a dive slate, and was fitted into one of many habitat categories, such as turf
algae (noted as T, less than 3cm), bushy algae (noted as B, anything larger than 3cm), red sponge
(noted as RS), black sponge, both alive and dead Posidonia (noted as POS, and PD respectively)
etc (similar to Villamor et al., 2010 but with less distinct categories). The categories were used in
conjunction with another group at STARESO Research Institute of Oceanography. Algal species
were only separated based on consistency (bushy, film, turf) and not based on their phylum
grouping. Only coralline algae was specifically noted due to the ease of identification. It was
further categorized into pink and red encrusting coralline algae (noted as EL and ER), while a
third group of encrusting algae was made for any that did not fall into the previous categories
(noted as EO). Invertebrates were often seen, but were not placed into any categories due to their
spatial distribution from Echinaster. The point the star was on was specially marked and placed
in another data set to see what exactly the star was on. Snorkelers were limited to depths of 20 ft,
so scuba divers were used to obtain data on stars deeper than 20 ft. Each diver was briefed on the
sampling methods to try and obtain an equal sampling style. Shallow stars were classified as 20
ft and above while deep stars were classified as 21 ft and below (there were no in-between stars).
Once the data was collected, it was imputed into Excel along with habitat data taken from
the harbor and surrounding areas in STARESO (thanks to another group at STARESO). Once
the data was combined, a PERMANOVA was run for habitat, depth, and habitat by depth. Next a
pair-wise test was generated using the data from habitat by depth. A cluster diagram was
produced also using the data. In addition, a SIMPER analysis was used to find the abundance and
major contributors to the differences. Using JMP, bar graphs were produced from average
abundance for each case. If the habitat composition changes drastically with depth and if greater
depths have a significant difference between shallower stars, I can conclude that the habitat
composition varies with depth and that Echinaster’s habitat usage also varies as a function of
depth.
Does Echinaster show a preference for a specific habitat type?
Doing observational surveys, Echinaster seems to be randomly spread throughout the
harbor and surrounding areas of STARESO with not much variability in habitat type. This seems
to be the case in most of the Mediterranean (Villamor et al., 2010). Using the sea star association
data taken from the previous question and combining it with the habitat data taken in and around
the harbor, they are compiled together to best represent the preference (if any) demonstrated by
Echinaster. The habitat data was taken from another group at STARESO using the same quadrat
method as myself. Using the data from the PERMANOVA ran in the previous hypothesis,
another pair-wise test was run comparing shallow habitat and sea star usage (Originally it was
run doing habitat and Echinaster separately), as well as deep habitat and sea star usage. With the
data, a SIMPER analysis was run in similar fashion as before to produce the average abundances
as well as the contributing percentage of each major contributing factor. With the data, JMP was
used to generate easy to read bar graphs of the abundances of the major contributors to the
difference. With this we can conclude that Echinaster does specialize in which the habitat it
associates with.
Does depth and orientation of Echinaster affect habitat cover preference?
Echinaster was seen at various depths as well as on both vertical and horizontal surfaces.
To test to determine if depth and orientation have an effect on what is around Echinaster; data
was used and collected in similar fashion to the first hypothesis. This was done by skin and scuba
diving in and around the harbor at STARESO research base using a quadrat to document the
habitat and also documenting the orientation of the star (horizontal or vertical). Unlike previous
questions, habitat data used from another group was not taken into account. Using Primer 6
software, a PERMANOVA was run in similar fashion as before generating data for orientation,
depth, and depth by orientation. Again, a SIMPER analysis was run to generate average
abundance and contributing percentages. Next, an MDS plot was graphed for both depth and
orientation to better show the differences and similarities among the various categories. Using
JMP, bar graphs were produced for average abundance, and the major contributing species. With
this, we can conclude that Echinaster found on both orientations types demonstrates a preference
for certain habitat cover types.
Results
Does habitat usage vary with depth?
There was a significant difference between both habitat and Echinaster (p-value < 0.001).
A difference in the amount of species or primary placeholders was also determined to be
significant with a p-value of < 0.001. Combining the variation of habitat from Echinaster and the
difference in depth together, it was discovered to be significant with a p-value of < 0.037.
Looking at Figure 2, Echinaster is in one cluster (deep and shallow branch off at around 23%),
and habitat in another cluster (deep and shallow branch off around 30%) branch off from each
other at 40% (Fig. 2). Deep and shallow in each cluster are different from one another, but are
more similar to each category inside their own cluster than they are from a category from another
cluster.
Group average
Resemblance: S17 Bray Curtis similarity
50
DepthCat
Shallow
Deep
Distance
40
30
20
10
Habitiat
Habitiat
Seastar
Seastar
0
Samples
Figure 2: A cluster diagram showing the differences among shallow and deep habitat, and sea stars
(Echinaster). The diagram shows that deep and shallow sea stars are different, and deep and shallow habitats
are also different. Shallow habitat is more similar to deep habitat than it is to either shallow or deep sea star.
This is the same for the sea stars as well.
Differences among shallow and deep sea stars are seen to be significant with a p-value of
< 0.009. The five main contributors to the differences between shallow and deep sea stars are turf
algae (30.69%), bushy algae (26.83%), encrusting lavender coralline algae (12.98%), Posidonia
(10.08%), red sponge (7.75%), and dead Posidonia (3.69%). Turf algae (noted as T) was seen to
be the most abundant for both deep and shallow stars, with very similar abundances, while bushy
algae (noted as B) was seen much more commonly associated with shallow stars (Fig. 3). The
remaining habitat cover types were all seen more commonly associated with deeper sea stars
which includes red sponge (noted as RS), and encrusting lavender coralline algae (noted as EL).
When shallow habitat was compared with deep habitat, a difference was seen with a pvalue of < 0.001. Looking at differences in habitat depth (Fig. 4), there were more contributing
factors that came into play such as encrusting other coralline algae (noted as EO)(4.52%), and
sand (noted as SA)(6.94%). Unlike the sea stars, bushy algae (26.56%) was determined to be the
main contributing factor rather than turf algae (14.91%). Dead Posidonia (noted as PD)(17.89%)
and living Posidonia (noted as POS)(17.72%) were seen to be much larger contributing factors
for habitat than they were for the sea stars, regardless of depth (Fig. 3, 4). While encrusting
lavender coralline algae was a decent contributor for differences among Echinaster, it was found
to hardly contribute at all in the habitat data (3.6%).
Figure 3: Average abundance of primary placeholders. Each species is one of the major contributors to the
differences among deep and shallow sea stars. Their average abundance is plotted on the y-axis, and this
shows the abundance of the organism
Figure 4: Average abundance of primary placeholder. Similar to figure 2, this shows the major contributors
to the difference in habitat as a function of depth.
Does Echinaster show a preference for a specific habitat type?
There was a significant difference between shallow habitat and shallow sea stars which
had a p-value of < 0.001. The same result occurred with deeper habitat and deeper sea stars (pvalue < 0.001).
The major contributing factors to the difference for deeper species were turf algae
(26.61%), bushy algae (19.73%), dead Posidonia (15.81%), Posidonia (14.95%), encrusting
lavender coralline algae (8.53%), red sponge (4.53%), and sand (4.26%). Turf was a huge
deciding factor among deep habitat and deep sea stars (Fig. 5). Deeper sea stars were
predominately seen around turf algae even though it wasn’t very common in the environment.
The next most common contributing factor seen was bushy algae which was very common (in
the environment) but wasn’t found very often associated with deeper Echinaster examples.
Echinaster was also found around red sponge, and encrusting lavender coralline algae even
though they were not very common (Fig. 5). Posidonia, and dead Posidonia were common
among the deeper habitats, yet the sea stars were not seen very often in conjunction with the sea
grass. Sand was also more commonly seen without the presence of Echinaster.
For shallow environments, turf (30.33%) is still the dominant contributor to the
difference, but the average abundances are much closer than in deeper environments (Fig. 6).
Bushy algae (27.97%) was again the second contributing factor, but relatively equal in the
amount of usage compared to what is seen. More bushy algae was seen in conjunction with
Echinaster at shallower depths (> 20 m). Posidonia (11.03%) and dead Posidonia (4.16%) were
less common in shallow environments, and even less common around Echinaster. Encrusting
lavender coralline algae (7.35%) is similar to the deeper environments where it is seen more
often around the sea star than by itself. Two new species, encrusting other coralline algae
(3.98%) and film algae (noted as F) (3.14%), were seen to contribute to the difference, and were
mainly seen in the absence of Echinaster. Again, much like the deeper environments, sand
(3.96%) was seen more often without sea stars.
Figure 5: Average abundance of primary
placeholders for deep sea stars and habitat. Each
species is a contributing factor to the difference
among habitat and the sea star
Figure 6: Average abundance of primary
placeholders for shallow sea stars and habitat.
Each species is a contributing factor to the
difference among habitat and the sea star
Does depth and orientation of Echinaster affect habitat cover preference?
Differences in orientation among Echinaster specimens were found to be significant (pvalue < 0.021). Differences in depth were also found to be significant with a p-value of < 0.029.
This varies slightly when no habitat data is taken into affect. When differences in orientation
between Echinaster and differences in depth were plotted together, it was found to be
insignificant (p-value < 0.426). Turf algae was the main contributor (most abundant) for both
depth and orientation with 30.64% and 31.16% respectively. The second contributor was bushy
algae (25.46% and 25.72%) followed by encrusting lavender coralline algae (13.3% and
12.63%), Posidonia (10.46% and 12.42%), red sponge (8.18% and 6.52%), and dead Posidonia
(3.99% and 3.17%) for both cases. Contribution percentages vary slightly for depth when habitat
data is not taken into affect. Bushy algae was seen very commonly on both orientations but more
often on horizontal substrates, while turf algae was also seen very often on both but more
common on vertical substrates (Fig. 7). Red sponges, and encrusting lavender coralline algae,
were predominately vertical, and Posidonia was predominately found on horizontal substrates
(Fig. 7).
Figure 7: Average abundance of primary place holders. Echinaster was found on both vertical and horizontal
substrates. This graph shows the major contributing factors to the differences seen between these orientation
types.
Figure 8: Average abundance of primary place holders. This shows differences in Echinaster as a function of
depth. Similar to Figure 3, but does not take habitat data into account.
The similarities and differences among deep and shallow sea stars and similarities and
differences of vertical and horizontal placement of stars were placed onto MDS plots (Fig. 9, 10).
There is some overlap on both graphs but the differences are still easy to spot.
Resemblance: S17 Bray Curtis similarity
2D Stress: 0.08
DepthCAT
Deep
Shallow
Figure 9: The effects of depth on habitat cover. Shown is deep (noted by green triangles) and shallow (blue
triangles) placement of stars found in and around Stareso.
Resemblance: S17 Bray Curtis similarity
2D Stress: 0.08
Orientation
V
H
Figure 10: The effects of orientation on habitat cover. Shown is vertical (noted by green triangles) and
horizontal (blue triangles) placement of stars found in and around Stareso.
Discussion
First, a significant p-value was determined for both habitat and Echinaster in regards to
depth. This leads to the idea that habitat does vary with depth and what Echinaster associates
with also varies with depth. As in most cases, turf and bushy algae were seen as the most
abundant habitat covers in association with Echinaster. Turf algae was seen almost equally in
both deep and shallow sea stars, but bushy algae was much more commonly associated with
shallower stars. Bushy algae was also more abundant in shallower habitats (< 20 ft), but the
difference was not as extreme compared to the difference between Echinaster. Instead there was
a large difference in the amount of turf algae seen as there was predominately more in shallower
environments. Posidonia was also found deeper for both Echinaster and habitat because
Posidonia is usually on the sea floor (Bakran-Petricioli et al., 2006). One possible reason bushy
algae was seen in shallower water could be due to the orientation of the star. Bushy algae was
more commonly found on vertical substrates and it is possible that with increasing depth, there
are fewer vertical rocks and cliffs that could provide protection for the algae. Various forms of
encrusting coralline algae were commonly found at shallower depths, but were found to be more
associated with deeper sea stars. This relationship however, deserves further research. It was
determined that bushy algae was more often found in shallower environments while Posidonia
(both dead and alive) was more often found at deeper depths (Fig. 3). The initial findings of this
paper conclude that the condition of Echinaster’s habitat does vary with depth; furthermore,
there does seem to be a difference between shallow and deep sea stars.
Secondly, Echinaster shows a few preferences in regards to associated species.
According to the data, deeper stars seem to seek out turf algae, encrusting lavender coralline
algae, and red sponge. Turf algae was the major contributor to the difference between habitat and
what Echinaster was associated with. In both cases, the amount of turf Echinaster associates with
is nearly twice as high as what was seen in the environment. Regardless of depth, these three
species were more frequently found with a star present than without. Villamor et al., (2010) were
unable to conclude a significant relationship between encrusting lavender coralline algae and the
abundance of Echinaster. However, the results found that there does seem to be some kind of
correlation between the two, seeing as the encrusting lavender coralline algae was typically seen
in association with Echinaster, but it is beyond the scope of this study to determine why the
correlation exists. Although, I cannot outright conclude encrusting lavender coralline algae is
mediated by Echinaster, the data provides some support that they are both associated with each
other. This could be due to the potential idea of protection provided by Echinaster as coralline
algae is common in areas associated with Echinaster. The significant p-values found provide
support for the idea that Echinaster does have a preference for specific species. Going back to
the specific hypothesis, we can provide support that Echinaster does seem to show a preference
for algal species over invertebrates (Fig. 5, 6).
Red sponge was found more often in association with Echinaster than it was by itself
(Fig. 5). While this was only seen at deeper depths (> 21 ft), this association may be due to
Echinaster preying on the sponge (Garcia-Raso et al., 1992, Maldonado et al., 1998). Various
studies were done looking at sponge mortality and potential predators (Maldonado et al., 1998),
and Echinaster was found to be associated with the sponge but was not found to be a factor for
mortality. Little is known about the feeding habits of the star and it is proposed that it eats
various sponges, but Maldonado et al., (1998) did not find a true connection between Echinaster
and the sponge. But now with the data that Echinaster seems to prefer sponge to many other
different habitat covers, there is the possibility that it is in fact a predator, but on a small scale, or
possibly a protector or mediator from potential predators. It is a possibility the star gains some
form of benefit by being in association with the sponge. The connection between red sponge and
Echinaster also appears to stronger at deeper depths (Fig. 5).
One study completed by Entrambasaguas et al., (2008) showed that Echinaster was found
to be more common in habitats with higher boulder density. Substrate data was taken for all sea
stars but was thrown out due to a categorical error with another group. From on observational
stand point, the sea stars were seen more frequently in more rocky habitats than in habitats with
sand, and Posidonia. Echinaster was commonly associated with red sponge, turf and bushy
algae, and encrusting coralline algae, which are all found on various forms of rocks. This could
be one of reasons why Entrambasaguas et al., (2000) found Echinaster to be more abundant and
more commonly found in rockier areas.
With significant p-values for difference in orientation, we can see that there are
differences in habitat types depending on whether Echinaster is on a vertical substrate or a
horizontal substrate. Thus, it was not a surprise to find that, when associated with Echinaster,
habitat cover types such as sand, and Posidonia were found more commonly on horizontal
surfaces, while sponge and encrusting lavender coralline algae were more prevalent with sea
stars on vertical surfaces (Villamor et al., 2010). During many observations, red sponge was
usually seen on vertical faces of rocks. A potential theory could be due to hiding in rocks from
various species of urchins due to predation (Maldonado et al., 1998). Habitat data was not taken
into effect, but we can draw some conclusions on the effect of orientation on habitat cover. It
was determined that orientation as a function of depth was insignificant so, a sea star that was
found deep and horizontal will not necessarily have a different assemblage of habitat than a
vertical shallow star. We know that depth and orientation is significant, but we are unable to
discover the significance when the two are combined. Looking at data taken from Figures 9 and
10, the overlap between some points showed that there are similarities between the depths and
orientation types. Yet the points were also spread out which shows that there were also
significant differences. The differences were significant enough that orientation does affect
habitat cover. Since there is a strong difference between both orientations, we can confirm the
specific hypothesis.
Synthesizing everything, a link between Echinaster and the habitat it associates with was
found. There does appear to be a significant difference in Echinaster found at different depths
(shallow versus deep), as well as seeing significant differences between the two orientation
types. There was also a preference for turf algae, encrusting lavender coralline algae, and red
sponge. By expanding on the ideas of both Villamor et al., (2010) and Maldonado et al., (1998)
this paper increases the amount of knowledge regarding the species and helps develop some
concrete data for future research of the species. The first step is recreating this study by utilizing
more precise methods regarding species composition. Instead of labeling categories such as turf
algae, bushy algae, etc, one should be more precise and have categorical data based on the genus
and possibly the species of the organism. This could greatly enhance the knowledge presently
available regarding Echinasters preference and depth differences; expanding the knowledge of
the species, we may determine whether Echinaster is a potential keystone species candidate or
not.
Little has been done regarding research of the species Echinaster sepositus. With the two
works done on habitat association and spatial distributions, we now have some data that helps
provide an idea regarding the types of habitats they prefer. What we don’t know is what kind of
feeding preference they have, and what exactly it is they eat. Most of the knowledge of
Echinaster comes from invertebrate guides of the Mediterranean, but these often contradict each
other. Before the topic of habitat association came up, I attempted to look at eating preference,
but was stopped due to lack of resources and various errors. The key to gaining more knowledge
of this species of Echinoderm is to first get a good idea (not just what a guide says) on what they
eat and whether they are generalist feeders or specialize on certain prey items.
Acknowledgments
I would like to thank the entire staff at STARESO Research Institute of Oceanography
for allowing me to perform my work and providing the necessary tools to help complete my
research. I would also like to thank Pete Raimondi and Giacomo Bernardi for allowing me this
great opportunity to take part in a real experiment and gain experience with working in the field.
Next, I would like to thank the TA’s, Gary Longo, Jimmy O’Donnell, and Kristin De Nesnera for
providing help with my research and the necessary tools for completing my assignments, and last
but not least, I would like to thank all the students in BIOE159 who made this class one of my
greatest achievements to date and my time in Corsica enjoyable.
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