waters. Ophiothrix spiculata is the most abundant and frequent species in the deep
waters (Fig. 2.6).
The Gulf of California is the second area in terms of diversity of echinoids, with
a total of 39 species (Solis-Marin et al. 2005), 12 of them in deep water. The most
characteristic are: Hesperocidaris asteriscus, H. perplexa, Arbacia incisa, Astropyga pulvinata, Centrostephanus coronatus, Echinometra vanbrunti, Lovenia
cordiformis, Encope wetmorei, E. micropora, Clypeaster europacificus, Agassizia
scrobiculata and Mellita grantii (Figs. 2.6 and 2.7).
This region holds the greatest diversity of the sea cucumbers in Mexico, with 64
species. Most (48 species) have wider distributions; they occur from the Gulf of
California to Central America or Galapagos Islands. Only two have a northern
distribution, from Alaska to the Gulf of California. The majority of the species
have shallow bathymetric distributions. Only 20 of the 58 species were collected
from depths greater than 200 m. The most characteristic species of sea cucumbers
are Holothuria (Selenkothuria) lubrica, H. (Thymiosycia) arenicola,
H. (T.) impatiens, H. (Halodeima) inornata, H. (Stauropora) fuscocinerea,
H. (Platyperona) difficilis, Isostichopus fuscus, Neothyone gibbosa and N. gibber
(Solis-Marin et al. 2005, 2009) (Fig. 2.8).
2.2.4 Mexican Pacific Ocean
On the Pacific coast, the crinoids are represented by four species (13.7 % of
the total for Mexico) off the western coast of the Baja California peninsula, and in
the polymetallic nodule fields near the Revillagigedo archipelago and the Clarion
Fig. 2.4 Number of
echinoderm species per class
in each region of Mexico.
C Caribbean, GM Gulf of
Mexico, P Pacific Ocean and
GC Gulf of California
2 The Echinoderms of Mexico
19