It looks like a Zuphea larva of a gnathiidae isopod, such as Paragnathia formica - not sure what species would be present in Persian Gulf though. see:

http://www.flickr.com/photos/56388191@N08/8584485239

can be an isopod: Gnathiidae

I can confirm it is an Isopod, belonging to the family Gnathiidae - but no more, sorry ;)

Looks like a gnathiid isopod

I think this is a juvenile gnathiid (Isopoda: Gnathiidae). The family is characterised by having 5 pairs of legs as opposed tot he usual seven. Juveniles (known as pranzia) are usually parasitic on fish but are very often found detached. Juveniles and females are difficult to identify to species even with specimens.

can be an Zuphea / Praniza larvae stadium of benthic Gnathiidae Isopods.

I am not a specialist of that group, but I have seen sometimes in plankton samples praniza larval stages (ectoparasites of fishes) of Gnathiidae. So I agree with Martin Atrill, it looks like a zuphea larval stage.

You can further look at this review:

Smit NJ, Davies AJ 2004. The curious life-style of the parasitic stages of Gnathiid isopods. Adv Parasitol 58:289-391

It looks like a gnathiidae isopod

looks like this gnathiidae family picture

http://m.static.newsvine.com/servista/imagesizer?file=boyleA1F7A95C-9380-D9D0-0EC2-7DF5986E8481.jpg&width=380

To me, this creature looks terrestrial in origin -- an insect of some kind.

Its an Isopod from family gnathidae

This is a female Gnathid isopod in it larval stage so it very difficult to identify it to a correct species so I would recommend leaving it at the general level

I think it is a Gnathiidae, Isopoda.

for what it is possible to see,

it is a Isopoda

a free stage of a ectoparasite

possibly family Gnatiidae

regards,

Genuario Belmonte

I agree that it is a gnathiid isopod (Isopoda: Gnathiidae) and probably a young female one. As an adult it is a benthic species and most probably a hyperbenthic one (swimming bottom-dependent organisms (mainly crustaceans) which perform,

with varying amplitude, intensity and regularity, seasonal or daily

vertical migrations into the water column (Brunel et al., 1978)). If it is at a larval stage it is considered to be zooplankton and therefore expected to be found in the water column. I have found several similar specimens in samples collected by using a hyperbenthic sledge at the sediment-water interface and in samples collected by using WP2 plankton net (vertical hauls) in the continental shelf and upper slope of Crete Island (eastern Mediterranean). In order to identify this specimen to species level you need a male one. So, I agree with Musa Khumalo that you cannot really identify this and I would also recommend to leave it as Gnathiidea (Isopoda).

I agree, its a zuphea larva of Gnathiidae isopod

It looks like a "praniza" larval stage of Isopods of the familiy Gnathiidae

yes, it's a praniza - Family Gnathiidae

The first three larval stages(praniza) of parasitic isopod (Gnathiidae) may resemble insects at first sight, because of their uniramous pereopods and their piercing mouth parts. Usually the lenght of early praniza is 800-900 micron, bigger that yours. I suggest a dissection to check the taxonomic keys for parassitic isopod (see Monod T. 1926).

This is not a crustacean! This is an insect. Looks like an Embiopteran known as web-spinners. They spin webs in debris and eat the debris.

I agree with my friends and I think that it is a gnathiid isopod (Isopoda: Gnathiidae)

More pictures would help giving detail of segments of the limbs and details of mouthparts. Given illustrations of gnathiid isopods available I accept the weakness of my statement that this is not a crustacean.

Thank you all for useful comments another picture from ventral side of the animal.

Two pairs of antennae, 5 pairs of legs, then definitely not an insect. Both the sample nature (plankton) and gross morphology point to a gnathiid isopod at the larval (zuphea or praniza) stage (large eyes are typical of gnathiid larvae) (see Smit & Davies 2004). One characteristic of gnathiid is the 5 pairs of pereopods as compared to the other isopods (7 pairs).

Dear Amir

At what depth did you placed the your sample gear and caught this sample?

Dear Mohammad,

Thank you for your interest. The specimens were retrieved from vertical plankton tows at 5m depth.

Praniza larva is correct.