Gorgona island (GOR ecoregion) also has a high number of records (41 species),
although it has been relatively less sampled. Among the coastal localities, the
tectonic estuary of Málaga Bay (BUE ecoregion) has the highest number of species
(25), followed by the localities along the north Pacific coast (e. g. Utría Bight,
19 species). All these localities are characterized by rocky areas as cliffs, shores,
and shallow bottoms. All localities also have high salinity (30 PSU or more).
In contrast, estuarine areas of the southern Pacific coast of Buenaventura Bay
(BUE), Tumaco Bay (TUM), the mouth of the Guapi River (NAY), and Mulatos
Beach (SAN), have a low number of species. But these species are always associated with the external zones of bays or estuaries. The low number of species in
these areas is the result of estuarine conditions (low salinity, high turbidity, and
sedimentation) and rarity of suitable rocky substrate.
Most species of echinoderms were found in more than one habitat. Rocky
substrates and coral reefs share some species of the cryptofauna, because of the
similarity of cavity structure of both rocky shores and coral framework. It is also
possible that physically contiguous habitats, such as cliffs and rocky shores, or
sandy beaches and mud flats also share some species. The moisture that remains in
some intertidal substrates during low tide allows the existence of some subtidal
species.
The species and the most important characteristics of groups of echinoderms of
different habitats are presented below.
Rocky Cliffs
Tectonic processes along the Pacific coast of Colombia have resulted in abundant
steep cliffs and to rocky shores with sloping platforms composed of boulders,
pebbles, and gravel formed by cliff erosion. In the northern basaltic cliffs the rocks
are igneous, very hard, and consolidated. In the southern part most rocks are
sedimentary (mudstones and shale), subject to rapid erosion by living organisms
Table 5.4 Number of species per class in each ecoregion of the Colombian Pacific Ocean
Ecoregion
Asteroidea
Ophiuroidea
Echinoidea
Holothuroidea
Total
PAN
6
4
6
1
17
BAU
5
5
4
2
16
BUE
9
12
8
2
31
NAY
8
1
4
1
14
SAQ
2
0
4
0
6
TUM
0
4
2
2
8
GOR
7
13
10
11
41
PAO
11
11
14
16
52
MAL
15
9
10
10
44
Total
34
30
28
32
124
Pacific North (PAN), Baudó (BAU), Buenaventura (BUE), Naya (NAY), Sanquianga (SAQ),
Tumaco (TUM), Gorgona (GOR), Malpelo (MAL) and Pacific Ocean (PAO)
5 Echinoderms of Colombia
169
although it has been relatively less sampled. Among the coastal localities, the
tectonic estuary of Málaga Bay (BUE ecoregion) has the highest number of species
(25), followed by the localities along the north Pacific coast (e. g. Utría Bight,
19 species). All these localities are characterized by rocky areas as cliffs, shores,
and shallow bottoms. All localities also have high salinity (30 PSU or more).
In contrast, estuarine areas of the southern Pacific coast of Buenaventura Bay
(BUE), Tumaco Bay (TUM), the mouth of the Guapi River (NAY), and Mulatos
Beach (SAN), have a low number of species. But these species are always associated with the external zones of bays or estuaries. The low number of species in
these areas is the result of estuarine conditions (low salinity, high turbidity, and
sedimentation) and rarity of suitable rocky substrate.
Most species of echinoderms were found in more than one habitat. Rocky
substrates and coral reefs share some species of the cryptofauna, because of the
similarity of cavity structure of both rocky shores and coral framework. It is also
possible that physically contiguous habitats, such as cliffs and rocky shores, or
sandy beaches and mud flats also share some species. The moisture that remains in
some intertidal substrates during low tide allows the existence of some subtidal
species.
The species and the most important characteristics of groups of echinoderms of
different habitats are presented below.
Rocky Cliffs
Tectonic processes along the Pacific coast of Colombia have resulted in abundant
steep cliffs and to rocky shores with sloping platforms composed of boulders,
pebbles, and gravel formed by cliff erosion. In the northern basaltic cliffs the rocks
are igneous, very hard, and consolidated. In the southern part most rocks are
sedimentary (mudstones and shale), subject to rapid erosion by living organisms
Table 5.4 Number of species per class in each ecoregion of the Colombian Pacific Ocean
Ecoregion
Asteroidea
Ophiuroidea
Echinoidea
Holothuroidea
Total
PAN
6
4
6
1
17
BAU
5
5
4
2
16
BUE
9
12
8
2
31
NAY
8
1
4
1
14
SAQ
2
0
4
0
6
TUM
0
4
2
2
8
GOR
7
13
10
11
41
PAO
11
11
14
16
52
MAL
15
9
10
10
44
Total
34
30
28
32
124
Pacific North (PAN), Baudó (BAU), Buenaventura (BUE), Naya (NAY), Sanquianga (SAQ),
Tumaco (TUM), Gorgona (GOR), Malpelo (MAL) and Pacific Ocean (PAO)
5 Echinoderms of Colombia
169