Research Article |
Corresponding author: Mariana Díaz-Santana-Iturrios ( marianadiazsani@gmail.com ) Corresponding author: Jesús Emilio Michel-Morfín ( emilio.michel@academicos.udg.mx ) Academic editor: Jiri Frank
© 2020 Alejandra Valdez-Cibrián, Mariana Díaz-Santana-Iturrios, Víctor Landa-Jaime, Jesús Emilio Michel-Morfín.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Valdez-Cibrián A, Díaz-Santana-Iturrios M, Landa-Jaime V, Michel-Morfín JE (2020) First detection of an ocellate octopus in the Revillagigedos ecoregion, a biodiversity hotspot located in the Tropical East Pacific Province. ZooKeys 986: 81-100. https://doi.org/10.3897/zookeys.986.53250
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The biodiversity of mollusks, particularly cephalopods, has not been exhaustively determined in the Revillagigedos ecoregion, which is a biodiversity hotspot for several marine groups located in the Tropical East Pacific Province. In our study, we detected and examined ocellate octopuses from Socorro and Clarion Islands, and determined their identity using morphological criteria and molecular data from two mitochondrial genes (COIII and COI). The taxon identified was Octopus oculifer, a species considered endemic to the Galapagos Archipelago. In addition, according to our analyses, O. mimus, O. hubbsorum and O. oculifer are very closely related and may represent a species complex comprised of three morphotypes. We found that the evolutionary relationships among octopuses are not determined by the presence of ocelli. This study is the first to report a clade represented by ocellate and non-ocellate species, in addition, the identity of cephalopods in the Revillagigedos was determined with analytical support.
Benthic octopus, Cephalopoda, Octopod, synonym, Tropical Pacific
Octopuses are soft-bodied cephalopods of the order Octopoda Leach, 1818, which comprises 13 families with around 300 pelagic or benthic species (
Ocelli are considered an important diagnostic trait within octopodids, and are defined as false eye-spots in the form of round or ovoid conglomerations of chromatophores that may possess an outer concentric dark or light ring and an iridescent blue, purple, gold, or green inner ring (
Determining the biodiversity of octopodids is relevant given that several species constitute fishery resources (4.8 million tons extracted during 2005–2014) (
The Revillagigedo Archipelago is located approximately 390 km southwest of the southern tip of the Baja California peninsula and 890 km west from Manzanillo harbor, between 17°39'19" and 20°00'31"N, and 110°04'41" and 115°28'17"W. The Archipelago is comprised of four volcanic islands: Roca Partida, San Benedicto, Clarion and Socorro (
Specimen number | DML (cm) | Sex | Maturity stage | Sampling site |
---|---|---|---|---|
1 | 6.5 | M | I | Clarion Island |
2 | 10 | F | I | Clarion Island |
3 | 7.5 | F | I | Clarion Island |
4 | 7 | M | I | Clarion Island |
5 | 8 | M | I | Clarion Island |
6 | 10 | F | N/A | Clarion Island |
7 | 8 | F | N/A | Clarion Island |
8 | 7.8 | F | N/A | Clarion Island |
9 | 7.5 | F | N/A | Clarion Island |
10 | 7 | F | N/A | Clarion Island |
11 | 8 | F | N/A | Clarion Island |
12 | 8 | M | N/A | Clarion Island |
13 | 10.5 | M | III | Clarion Island |
14 | 8.8 | F | N/A | Clarion Island |
15 | 7.3 | F | N/A | Clarion Island |
16 | 6.6 | F | N/A | Clarion Island |
17 | 3.1 | F | N/A | Clarion Island |
18 | 7.5 | F | N/A | Clarion Island |
19 | 6 | F | N/A | Clarion Island |
20 | 6.5 | F | N/A | Clarion Island |
21 | 10.5 | M | III | Clarion Island |
22 | 10 | F | II | Clarion Island |
23 | 7.5 | M | III | Clarion Island |
24 | 6.5 | F | I | Clarion Island |
25 | 6.5 | F | I | Clarion Island |
26 | 8 | F | II | Clarion Island |
27 | 9 | F | II | Clarion Island |
28 | 5.5 | F | I | Clarion Island |
29 | 7 | F | I | Clarion Island |
30 | 5.6 | F | I | Clarion Island |
31 | 5.7 | F | I | Clarion Island |
32 | 6.5 | F | I | Clarion Island |
33 | 6 | F | I | Clarion Island |
34 | 6.8 | M | II | Clarion Island |
35 | 6.8 | F | II | Clarion Island |
36 | 7.3 | F | II | Clarion Island |
37 | 8.3 | F | II | Clarion Island |
38 | 7.5 | M | II | Clarion Island |
39 | 6.9 | M | II | Clarion Island |
40 | 6.5 | F | I | Clarion Island |
41 | 6.5 | F | I | Clarion Island |
42 | 9 | F | II | Socorro Island |
43 | 6.3 | F | II | Socorro Island |
44 | 9 | F | III | Socorro Island |
45 | 8 | F | II | Socorro Island |
46 | 11.5 | M | III | Socorro Island |
47 | 11 | M | III | Socorro Island |
48 | 11 | M | III | Socorro Island |
49 | 12.8 | F | III | Socorro Island |
In Socorro Island, specimens were captured in each location by free and scuba diving using a hook; and in Clarion Island, octopuses were collected with a hook in the rocky intertidal during the lowest tide of each sampling site and day. Octopuses were sacrificed right after fishing. Individuals were sexed according to the presence (male) or absence (female) of a hectocotylized arm. Maturity stages for males and females were determined with the same criterion considered by
The dorsal mantle length (DML) and total weight (TW) were recorded to determine the length-weight relationship (LWR). Class intervals were determined following the Sturge’s rule. The following potential equation was employed to evaluate LWR:
TW= a * DMLb
where: TW = dependent variable (total weight), a = coefficient of proportionality, DML = independent variable (dorsal mantle length), b = allometry coefficient (weight per unit of length).
The type of growth was estimated based on Student’s t-test for the “b” values obtained from the model and compared to a theoretical value of b=3 which represents isometric growth.
For the molecular approach, sequences deposited in GenBank (Table
All partial COIII and COI sequences were assembled and edited using BIOEDIT 7.2.6 software (
Accession numbers of sequences (COIII and COI) obtained from GenBank of the octopodid species and specimens evaluated in this study.
The individuals analyzed belonged to the genus Octopus Cuvier, 1797; these presented an ink sac and suckers in a two-row arrangement. The specimens presented ocelli (Fig.
Diagnostic features of species of the genus Octopus reported for the Revillagigedo islands and ocellate species of the world. Species identified in bold.
Species | Arm index | Arm formula | Sucker counts | Ocelli | Lamellae per demibranch | Funnel organ shape |
---|---|---|---|---|---|---|
O. bimaculatus | 4 to 5 | 3>2>4>1 | 200 to 320 | Yes | 8 to 10 | W |
O. oculifer | 3.5 to 4.5 | 3>2>4>1 | 230 to 280 | Yes | 8 to 10 | W |
O. hubbsorum | 3 to 4 | 3>2>4>1 | 240 | No | 9 to 11 | W |
O. bimaculoides | 3 to 3.5 | 3>2>4>1 | 140 to 190 | Yes | 8 to 10 | W |
O. maya | 3 to 4.5 | 3>4=2>1 | N/A | Yes | 9 to 10 | W |
O. cyanea | 4 to 6 | 4=3=2>1 | 450 to 500 | Yes | 9 to 11 | W |
A. exannulatus | 2 to 3 | 3>4>2>1 | 120 to 190 | Yes | 8 | W |
A. kagoshimensis | 2 to 3 | 4=3=2>1 | 150 to 170 | Yes | 8 to 9 | W |
A. mototi | 2.5 to 3 | 3=4>2>1 | 140 to 170 | Yes | 9 to 11 | W |
A. neglectus | 2 to 3 | 4=3>2>1 | 110 to 125 | Yes | 7 to 8 | W |
A. rex | 2 to 3 | 4>3>2>1 | 134 to 184 | Yes | 8 to 9 | W |
A. siamensis | 2 to 3 | 4=3>2>1 | 100 to 140 | Yes | 7 to 8 | W |
A. ovulum | N/A | 4=3=2>1 | 59 to 70 | Yes | 15 to 17 | W |
The morphological features observed in the octopuses evaluated in this study are shown in Fig.
Morphological features. Morphological features of Octopus oculifer from the Revillagigedo Archipelago A dorsal view; H: hectocotylus, LI-IVA: left arms I-IV B ventral view; LI-IVA: left arms I-IV C ligula Lg and calamus Cl D H: hectocotylus, radulae E funnel organ shape F demibranch G upper and lower beaks.
Coloration patterns. Coloration patterns observed in live individuals of Octopus oculifer from the Revillagigedo Archipelago A pale body with few reddish/brown spots randomly placed throughout the mantle and arms, entire body with a rugose aspect B brown and smooth body with large well-defined white ovals throughout mantle and arms C rugose and reddish body with large cream ovals of different size D red and smoother (still rugose) body with lesser number of cream ovals of different size E dark red body without ovals and a smooth skin.
The phylogenetic trees of COIII and COI-gene sequences showed that the specimens from the Revillagigedo Archipelago belong to a clade associated with the ocellated octopus O. oculifer and the non-ocellate octopuses O. hubbsorum and O. mimus (Figs
Genetic distances among octopuses collected and reported in the Revillagigedo Archipelago (RA) and ocellate and non-ocellate octopuses of the world estimated for a fragment of COIII gene sequences. Octopus maya (Oct may), Amphioctopus exalatus (Amp exa), Amphioctopus fangsiao (Amp fan), Amphioctopus kagoshimensis (Amp kag), Amphioctopus mototi (Amp mot), Amphioctopus neglectus (Amp neg), Amphioctopus ovulum (Amp ovu), Octopus cyanea (Oct cya), Our specimens (Our spe), Octopus oculifer (Oct ocu), Octopus hubbsorum (Oct hub), Octopus bimaculoides (Oct bdes), Octopus bimaculatus (Oct btus), Enteroctopus dofleini (Ent dof), Octopus insularis (Oct ins), Octopus vulgaris (Oct vul), Octopus tetricus (Oct tet), Octopus fitchi (Oct fit), Robsonella fontaniana (Rob fon), Hapalochlaena fasciata (Hap fas), Abdopus aculeatus (Abd acu), Ameloctopus litoralis (Ame lit), Eledone cirrhosa (Ele cirr), Bathypolypus sponsalis (Bat spo), Muusoctopus longibrachis (Muu lon) and Octopus mimus (Oct mim).
Sp | Oct | Amp | Amp | Amp | Amp | Amp | Amp | Oct | Our | Oct | Oct | Oct | Oct | Ent | Oct | Oct | Oct | Oct | Rob | Hap | Abd | Arne | Ele | Bat | Muu | Oct |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
may | exa | fan | kag | mot | neg | ovu | cya | spe | ocu | hub | bdes | bws | dof | ins | vul | tet | fit | fon | fas | acu | lit | cir | spo | lon | mim | |
Oct may | 0% | |||||||||||||||||||||||||
Amp exa | 17.9% | |||||||||||||||||||||||||
Amp fan | 15.5% | 14.1% | ||||||||||||||||||||||||
Amp kag | 19.9% | 15.2% | 12.0% | |||||||||||||||||||||||
Amp mot | 17.9% | 13.5% | 12.9% | 17.0% | ||||||||||||||||||||||
Amp neg | 16.4% | 15.5% | 11.4% | 14.7% | 14.1% | |||||||||||||||||||||
Amp ovu | 18.5% | 15.0% | 15.4% | 14.7% | 14.4% | 14.2% | ||||||||||||||||||||
Oct cya | 18.2% | 17.0% | 15.8% | 18.2% | 18.5% | 19.9% | 17.6% | |||||||||||||||||||
Our spe | 13.3% | 15.7% | 15.4% | 18.7% | 16.2% | 16.2% | 15.1% | 14.6% | ||||||||||||||||||
Oct ocu | 13.5% | 16.1% | 15.8% | 18.5% | 16.4% | 15.8% | 14.7% | 15.0% | 0.4% | |||||||||||||||||
Oct hub | 13.2% | 15.8% | 15.5% | 18.8% | 16.1% | 16.1% | 15.0% | 14.7% | 0.1% | 0.3% | ||||||||||||||||
Oct bdes | 10.3% | 17.0% | 15.2% | 19.1% | 15.5% | 14.7% | 15.1% | 15.2% | 8.9% | 9.1% | 8.8% | |||||||||||||||
Oct bws | 10.7% | 15.5% | 15.8% | 19.1% | 16.7% | 15.0% | 14.7% | 16.1% | 8.5% | 8.7% | 8.4% | 4.8% | ||||||||||||||
Ent dof | 20.8% | 20.2% | 17.9% | 17.6% | 19.6% | 17.0% | 19.9% | 19.2% | 17.7% | 17.3% | 17.6% | 16.9% | 17.0% | |||||||||||||
Oct ins | 11.1% | 15.2% | 14.4% | 18.5% | 16.1% | 15.0% | 15.0% | 16.4% | 8.3% | 8.5% | 8.2% | 9.7% | 8.4% | 18.8% | ||||||||||||
Oct vul | 14.1% | 16.7% | 15.2% | 19.4% | 16.7% | 16.7% | 17.4% | 17.0% | 12.1% | 12.3% | 12.0% | 11.6% | 11.4% | 21.0% | 11.7% | |||||||||||
Oct tet | 15.0% | 17.3% | 15.5% | 20.2% | 18.5% | 15.8% | 18.8% | 18.8% | 13.3% | 13.5% | 13.2% | 12.9% | 12.2% | 21.4% | 12.3% | 3.4% | ||||||||||
Oct fit | 21.4% | 18.5% | 17.9% | 17.9% | 16.1% | 18.2% | 19.1% | 19.9% | 18.3% | 18.5% | 18.2% | 18.2% | 19.1% | 20.5% | 18.2% | 20.1% | 19.9% | |||||||||
Rob fon | 20.5% | 19.4% | 18.8% | 19.4% | 19.4% | 21.4% | 20.5% | 18.8% | 17.2% | 17.6% | 17.3% | 18.5% | 19.2% | 19.8% | 19.1% | 19.1% | 19.6% | 20.2% | ||||||||
Hap fas | 19.5% | 18.5% | 13.2% | 15.5% | 15.7% | 13.9% | 15.4% | 17.7% | 17.5% | 17.4% | 17.4% | 16.7% | 16.7% | 19.1% | 16.7% | 15.8% | 16.3% | 17.6% | 20.5% | |||||||
Abd acu | 18.9% | 17.2% | 17.0% | 18.5% | 18.9% | 18.0% | 17.7% | 16.6% | 15.3% | 15.5% | 15.2% | 16.4% | 17 6% | 21.7% | 16.0% | 16.4% | 17.7% | 19.1% | 19.9% | 18.5% | ||||||
Arne lit | 17.9% | 17.9% | 18.2% | 19.6% | 17.6% | 17.0% | 18.0% | 17.9% | 14.8% | 15.0% | 14.7% | 13.5% | 13.9% | 18.6% | 13.5% | 14.2% | 14.1% | 19.4% | 19.6% | 18.9% | 18.3% | |||||
Ele cir | 22.3% | 22.3% | 20.5% | 22.0% | 20.8% | 19.9% | 21.6% | 19.6% | 19.5% | 19.6% | 19.4% | 21.4% | 21.4% | 21.1% | 18.8% | 20.7% | 20.5% | 22.0% | 22.6% | 18.5% | 20.7% | 22.9% | ||||
Bat spo | 19.4% | 20.8% | 16.1% | 18.2% | 20.8% | 19.9% | 18.6% | 18.2% | 18.1% | 18.5% | 18.2% | 17.6% | 19.5% | 17.4% | 18.5% | 22.1% | 22.6% | 19.4% | 18.5% | 21.8% | 22.0% | 19.1% | 20.5% | |||
Muu lon | 21.1% | 19.1% | 16.4% | 17.0% | 17.6% | 16.4% | 18.5% | 19.6% | 18.1% | 18.5% | 18.2% | 16.4% | 17.3% | 7.8% | 19.6% | 21.6% | 22.3% | 18.8% | 19.4% | 18.6% | 21.4% | 18.8% | 19.1% | 15.5% | ||
Oct mim | 13.5% | 15.4% | 15.2% | 18.8% | 16.0% | 16.1% | 14.8% | 14.5% | 0.7% | 1.0% | 0.7% | 9.1% | 8.8% | 18.0% | 8.2% | 12.2% | 13.2% | 18.2% | 17.7% | 17.7% | 15.5% | 15.1% | 19.4% | 18.2% | 18.2% | 0% |
Genetic distances among octopuses collected and reported in the Revillagigedo Archipelago (RA) and ocellate and non-ocellate octopuses of the world estimated for a fragment of COI gene sequences. Octopus maya (Oct may), Amphioctopus exalatus (Amp exa), Amphioctopus fangsiao (Amp fan), Amphioctopus kagoshimensis (Amp kag), Amphioctopus mototi (Amp mot), Amphioctopus neglectus (Amp neg), Amphioctopus ovulum (Amp ovu), Octopus cyanea (Oct cya), Our specimens (Our spe), Octopus hubbsorum (Oct hub), Octopus bimaculoides (Oct bdes), Octopus bimaculatus (Oct btus), Enteroctopus dofleini (Ent dof), Octopus insularis (Oct ins), Octopus vulgaris (Oct vul), Octopus tetricus (Oct tet), Octopus fitchi (Oct fit), Robsonella fontaniana (Rob fon), Hapalochlaena fasciata (Hap fas), Abdopus aculeatus (Abd acu), Ameloctopus litoralis (Ame lit), Bathypolypus sponsalis (Bat spo), Eledone cirrhosa (Ele cirr), Muusoctopus longibrachis (Muu lon) and Octopus mimus (Oct mim).
Species | Oct | Amp | Amp | Amp | Amp | Oct | Our | Oct | Oct | Oct | Ent | Oct | Oct | Oct | Oct | Rob | Hap | Abd | Ame | Bat | E/e | Muu | Oct |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
may | fan | kag | neg | ovu | cya | spe | hub | bdes | btus | dof | ins | vu/ | tet | fit | Jon | fas | acu | lit | spa | cir | lon | mim | |
Oct may | 0% | ||||||||||||||||||||||
Amp fan | 15.0% | ||||||||||||||||||||||
Amp kag | 17.5% | 13.9% | |||||||||||||||||||||
Amp neg | 17.7% | 15.8% | 14.1% | ||||||||||||||||||||
Amp ovu | 16.7% | 13.6% | 13.8% | 14.5% | |||||||||||||||||||
Oct cya | 13.2% | 15.8% | 14.8% | 16.2% | 14.0% | ||||||||||||||||||
Our spe | 7.3% | 14.0% | 18.0% | 17.2% | 17.5% | 14.8% | |||||||||||||||||
Oct hub | 7.3% | 14.2% | 18.0% | 17.4% | 17.5% | 14.6% | 0.2% | ||||||||||||||||
Oct bdes | 10.9% | 14.1% | 15.5% | 17.9% | 16.9% | 15.4% | 9.6% | 9.6% | |||||||||||||||
Oct btus | 10.5% | 14.0% | 16.5% | 18.1% | 17.4% | 14.2% | 9.8% | 9.8% | 6.2% | ||||||||||||||
Ent dof | 18.0% | 18.9% | 19.8% | 17.5% | 16.4% | 16.2% | 18.6% | 18.6% | 19.1% | 19.1% | |||||||||||||
Oct ins | 7.7% | 14.8% | 16.5% | 16.6% | 16.1% | 13.4% | 5.9% | 5.9% | 9.7% | 9.7% | 17.6% | ||||||||||||
Oct vul | 14.3% | 16.4% | 16.0% | 15.8% | 17.6% | 16.4% | 12.8% | 13.0% | 14.3% | 13.6% | 18.6% | 11.8% | |||||||||||
Oct tet | 14.3% | 15.7% | 16.6% | 15.1% | 16.7% | 15.1% | 12.1% | 12.3% | 14.7% | 14.5% | 17.1% | 11.8% | 3.4% | ||||||||||
Oct fit | 17.1% | 15.6% | 16.9% | 17.3% | 15.9% | 15.9% | 15.9% | 15.9% | 18.7% | 18.8% | 18.1% | 16.7% | 17.1% | 15.8% | |||||||||
Rob Jon | 16.0% | 17.5% | 16.7% | 15.6% | 15.9% | 16.6% | 16.4% | 16.1% | 16.1% | 17.3% | 14.1% | 15.8% | 17.8% | 16.8% | 15.2% | ||||||||
Hap fas | 16.1% | 14.1% | 14.8% | 17.1% | 17.0% | 16.1% | 16.4% | 16.4% | 15.7% | 16.0% | 19.4% | 15.5% | 16.1% | 15.3% | 17.6% | 17.4% | |||||||
Abd acu | 16.8% | 17.0% | 17.3% | 16.5% | 18.2% | 13.5% | 16.5% | 16.5% | 18.2% | 16.1% | 20.9% | 16.1% | 16.9% | 17.0% | 16.4% | 16.8% | 16.8% | ||||||
Ame lit | 18.6% | 18.9% | 19.0% | 18.6% | 16.8% | 18.2% | 18.9% | 18.7% | 18.0% | 18.8% | 17.3% | 17.3% | 17.7% | 17.3% | 16.2% | 17.1% | 18.2% | 18.5% | |||||
Bat spo | 18.1% | 17.3% | 16.7% | 16.0% | 15.8% | 15.8% | 18.2% | 18.2% | 17.5% | 18.4% | 14.9% | 17.5% | 17.9% | 16.8% | 18.6% | 14.1% | 18.1% | 17.3% | 19.4% | ||||
Ele cir | 16.4% | 16.9% | 16.8% | 19.7% | 18.7% | 15.1% | 16.9% | 16.9% | 16.9% | 17.2% | 17.6% | 17.0% | 16.7% | 14.9% | 16.8% | 15.3% | 18.1% | 16.0% | 17.8% | 16.4% | |||
Muu lon | 19.3% | 20.3% | 18.6% | 17.4% | 16.9% | 17.4% | 20.5% | 20.5% | 21.0% | 19.7% | 9.4% | 19.5% | 18.5% | 17.4% | 20.0% | 14.8% | 19.1% | 19.5% | 19.8% | 15.6% | 17.4% | ||
Oct mim | 7.4% | 14.1% | 17.9% | 17.5% | 17.4% | 14.7% | 0.5% | 0.5% | 9.5% | 9.5% | 18.7% | 5.8% | 12.9% | 12.2% | 15.8% | 16.2% | 16.2% | 16.6% | 18.8% | 18.1% | 17.0% | 20.1% | 0% |
In this study we analyzed octopuses from the Revillagigedo Archipelago in an attempt to increase knowledge concerning cephalopods in this geographic area. We identified the octopuses to the species level primarily, according to their morphological attributes, and secondarily, using partial sequences of COIII and COI genes following
For octopodids, particularly for the species evaluated in this study, a great deal of the taxonomic confusion is related to the fact that the morphological attributes are not standardized among species and that the diagnoses of octopodids from the northeastern Pacific had not been updated since the species descriptions, except for the validation of O. bimaculatus and O. bimaculoides within the genus Octopus performed by
The endemism and geographic distribution of O. oculifer restricted to the Galapagos Islands was well documented (
In addition, the molecular analyses of partial COIII and COI sequences strongly evidenced that O. oculifer, O. hubbsorum, and O. mimus are very closely related (inter-specific distance lower than 1%) and it is highly likely that these taxa are conspecific and represent a species complex comprised by three morphotypes. However, our finding should be further confirmed with type material (when available) and complete re-descriptions must be performed to support that these taxa are the same species. Moreover, the closer evolutionary relationships found between ocellated and non-ocellated octopuses compared to the relationships among non-ocellated octopuses indicate that the presence of ocelli is not a determinant character in octopodid classification and therefore, it should not be considered a diagnostic attribute.
In this research, we conclude that according to our integrative species identification, the specimens collected in the Revillagigedo Archipelago are Octopus oculifer. According to our molecular analyses the non-ocellate O. hubbsorum and O. mimus and the ocellate O. oculifer are very closely related and might constitute a single species comprised of three morphotypes. In addition, ocelli should not be considered a diagnostic attribute for octopodids but rather a supplemental character.
The authors thank Rosa Maria Morelos for her support in making the molecular procedures available. We are also grateful to the team integrated by Alfredo Castillo-Guerrero, Salvador Hernández-Vázquez, Daniel Portillo, Andrés Baez, Caren Aguilera, Gloria López, Jazmín Anguiano, Ramón Morales, Gerardo Martínez and Diego González for their help in the field and collection of data. We thank Alejandro Gonzalez-Leija, Director of the Revillagigedo National Park, for his assistance in obtaining the permits to visit the Archipelago and the authorities of the Mexican Navy for their help onboard the ships and in the facilities of Socorro and Clarion.