It also had a different number and distribution of photophores
, which are the tiny cup-shaped organs that give lanternsharks the ability to glow.
1977) and the most speciose, including almost 250 species referred to as lanternfish due to a variety of luminous organs, among which photophores
are the most characteristic (Nelson, 2006).
The intestinal photophore
was visible only in some individuals because most specimens were in poor condition.
Hyaloteuthis, Eucleoteuthis and Ommastrephes are relatively rare in the ETP (all the molecularly identified ommastrephids in this study were Sthenoteuthis or Dosidicus; see also Yatsu (3)), and only 9 specimens were tentatively identified as Eucleoteuthis and 2 specimens were tentatively identified as Ommastrephes by proboscis suckers and photophores
(6 others were excluded from Dosidicus or Sthenoteuthis but were too small to be assignable to the other 3 genera).
Various forms, particularly those affecting hydrodynamic flow, may be associated with sensory organs--for example, pit organs and photophores
(Reif, 1978; Gomahr et al.
Biophysicist Alison Sweeney of the University of Pennsylvania had hypothesized that the cells, called photophores
, act like microscopic cables that channel the bioluminescent glow of the squid down or out in a specific direction.
The most complex photophores
have complex lenses to focus the light produced, reflectors to concentrate it, shades to turn it off at will, filters to modify the light's color (originally blue-green and cold, consisting only of the radiation of the color emitted, unlike electric light bulbs which emit much of the light in the form of heat), muscles to move the sacs, and some species can even empty them.
This species also has a number of ventrally directed photophores
: a series along the core of the four ventral arms; an arm base organ on arm pairs II, III, and IV; a pair of small medial head organs; a photophore
posterior to each eye; a pair of visceral photophores
situated ventral to the ink sac; and a single posterior "tail" organ (Young, 1972).
The two were chosen to provide a range of photophore
The advantage of an integrating chamber is that the measurement of emitted light is minimally affected by photophore
or animal position.
is a raised papilla-like structure partially embedded in the connective tissue of the arm.
Those on the third maxilliped represent the simplest level of organization, consisting of single photophore
units each containing a single photocyte.