The cephalopods are the largest nektonic invertebrates. Some common species in
the Alboran Sea are Loligo vulgaris, L. forbesii, Alloteuthis media, Abralia verany,
Illex coindetii, Todarodes sagittatus, Ommastrephes bartramii, Sthenoteuthis
pteropus, Brachioteuthis riisei and Ancistroteuthis lichtensteinii (Guerra 1992;
Templado et al. 1993; González and Sánchez 2002; Quetglas et al. 2013). They
are important predators and are also agents for the transfer of nutrients from the
pelagic community to higher trophic levels.
Among the decapod crustaceans, a good number of caridean (suborder
Dendrobranchiata) and penaoidean species (suborder Pleocyemata) form a characteristic trophic guild of macroplankton-epibenthic feeders that mainly dwell near the
bottom (nektobentonic species) but have sharp diel vertical migrations into upper
water layers during the night (Judkins 2014). These migrations behaviour have an
important role in the transfer of matter and energy from the upper primary productive
layers of the sea, where these species come up to feed during the night, down to the
epibenthic community of the continental slope, where they dwell during the day
(Simão et al. 2015).
The Alboran Sea is characterized by the dominance of caridean pandalid shrimps,
which reach in this area the highest values of abundance and show a trend to have a
shallower distribution compared with other areas (Carbonell and Abelló 1998;
Fanelli and Cartes 2004). The most common Alboran pandalids are Chlorotocus
crassicornis, Plesionika acanthonotus, P. heterocarpus and P. martia. Two very
common shrimps of the suborder Pleocyemata are the pasiphaeids Pasiphaea sivado
and P. multidentata (Simão et al. 2015). Both species also show a shallower
bathymetric range in the westernmost region of the Algerian shore than in other
sectors, linked to the occurrence of upwelling areas on the northwestern edges of the
Alboran Sea.
The other important group of benthopelagic shrimps is that formed by species of
Sergestoidea and Penaeoidea, also well represented in the Alboran Sea. The most
common are the penaeoideans Gennadas elegans and Funchalia villosa and the
sergestoideans Robustosergia robusta, Sergia japonica, Allosergestes sargassi,
Parasergestes vigilax and Eusergestes arcticus (García Raso 1982; García Raso
et al. 2018).
Among the swimming crabs, the portunid Polybius henslowii deserves special
mention by its uncommon behaviour. It is a benthopelagic species distributed along
the eastern Atlantic coasts from the British Islands to the Alboran Sea and southern
Morocco. Usually of benthic habits, this crab moves periodically to surface waters,
forming large pelagic swarms mainly composed of females, which excludes a
reproductive migration and might be related to feeding. During this pelagic period,
this species feeds on fish, squids or other crustaceans (Signa et al. 2008). Some of
these surface swarms have been observed off the Moroccan coast near the Strait of
Gibraltar from May to August (Ocaña et al. 2006a). These authors pointed out that
the large concentrations of P. henslowii are the main source for the diet of the
loggerhead turtles in this area and for a number of other species including gulls and
pelagic and benthopelagic fishes.
10 Invertebrates: The Realm of Diversity
397
the Alboran Sea are Loligo vulgaris, L. forbesii, Alloteuthis media, Abralia verany,
Illex coindetii, Todarodes sagittatus, Ommastrephes bartramii, Sthenoteuthis
pteropus, Brachioteuthis riisei and Ancistroteuthis lichtensteinii (Guerra 1992;
Templado et al. 1993; González and Sánchez 2002; Quetglas et al. 2013). They
are important predators and are also agents for the transfer of nutrients from the
pelagic community to higher trophic levels.
Among the decapod crustaceans, a good number of caridean (suborder
Dendrobranchiata) and penaoidean species (suborder Pleocyemata) form a characteristic trophic guild of macroplankton-epibenthic feeders that mainly dwell near the
bottom (nektobentonic species) but have sharp diel vertical migrations into upper
water layers during the night (Judkins 2014). These migrations behaviour have an
important role in the transfer of matter and energy from the upper primary productive
layers of the sea, where these species come up to feed during the night, down to the
epibenthic community of the continental slope, where they dwell during the day
(Simão et al. 2015).
The Alboran Sea is characterized by the dominance of caridean pandalid shrimps,
which reach in this area the highest values of abundance and show a trend to have a
shallower distribution compared with other areas (Carbonell and Abelló 1998;
Fanelli and Cartes 2004). The most common Alboran pandalids are Chlorotocus
crassicornis, Plesionika acanthonotus, P. heterocarpus and P. martia. Two very
common shrimps of the suborder Pleocyemata are the pasiphaeids Pasiphaea sivado
and P. multidentata (Simão et al. 2015). Both species also show a shallower
bathymetric range in the westernmost region of the Algerian shore than in other
sectors, linked to the occurrence of upwelling areas on the northwestern edges of the
Alboran Sea.
The other important group of benthopelagic shrimps is that formed by species of
Sergestoidea and Penaeoidea, also well represented in the Alboran Sea. The most
common are the penaeoideans Gennadas elegans and Funchalia villosa and the
sergestoideans Robustosergia robusta, Sergia japonica, Allosergestes sargassi,
Parasergestes vigilax and Eusergestes arcticus (García Raso 1982; García Raso
et al. 2018).
Among the swimming crabs, the portunid Polybius henslowii deserves special
mention by its uncommon behaviour. It is a benthopelagic species distributed along
the eastern Atlantic coasts from the British Islands to the Alboran Sea and southern
Morocco. Usually of benthic habits, this crab moves periodically to surface waters,
forming large pelagic swarms mainly composed of females, which excludes a
reproductive migration and might be related to feeding. During this pelagic period,
this species feeds on fish, squids or other crustaceans (Signa et al. 2008). Some of
these surface swarms have been observed off the Moroccan coast near the Strait of
Gibraltar from May to August (Ocaña et al. 2006a). These authors pointed out that
the large concentrations of P. henslowii are the main source for the diet of the
loggerhead turtles in this area and for a number of other species including gulls and
pelagic and benthopelagic fishes.
10 Invertebrates: The Realm of Diversity
397