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which has penetrated into the great depths and its features enable this species to
inhabit depths above 3000 m where the environmental conditions are different. The
base of the continental slope in the NE Atlantic occurs at ~ 3300 m (Rice et al., 1991).
Howell et al. (2002) proposed that this may represent a barrier to abyssal species.
They also found a tenuous relation between the depth at which abyssal fauna starts to
appear and the depth at which North Atlantic Deep Water (NADW) and Modified
Antarctic Bottom Water (MABW) meet between 3000 and 3500 m. Rogers (2000)
provided evidence; which suggest that many abyssal groups have originated in the
Southern Ocean, where Antarctic Bottom Water originates.
The abyssal zone is inhabited by asteroid species with reproductive features
indicative of equilibrium K strategists (Winemiller and Rose, 1992), which have low
fecundity, large egg size and expected high juvenile survivorship, although their large
body size makes them more comparable to the classical K strategists (MacArthur and
Wilson, 1967; Pianka, 1970), and they are characteristic inhabitants of constant
environments (Winemiller and Rose, 1992; McCann and Shuter, 1997).
As Ramirez-Llodra (2002) concluded, the species that have colonized the
different deep-sea environments have to be well adapted to their habitat in order to be
successful and persistent. In the deep NE Atlantic the habitat has selected for species
with specific reproductive traits, which provide them with successful and
advantageous life history strategies (Eckelbarger, 1994; Eckelbarger and Watling,
1995) as can be clearly observed in the upper bathyal zone between 700 and 1100 m,
where the environmental conditions have selected for small species with low
fecundity and large eggs, plus habits related directly or indirectly with suspension
feeding. This species exhibit reproductive features associated to the opportunistic
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