Aeginina longicornis Krøyer, 1842
Caprellid, “Ghost” or “Skeleton” shrimps, so called for their skeletal appearance. Amphipod crustaceans, easily distinguished by the elongate stick-like body form and reduction of the abdominal appendages. Head is generally fused with pereonite 1. Pereopods on first 2 segments (pereonites) are most flexible and called gnathopods; gnathopods 2 being the largest, used in defense, feeding and substrate attachment. In many species pereopods 3 and 4 may also be reduced or absent. Gills on pereonites 3 + 4, rarely on pereonite 2. Pereopods 5 - 7 much smaller than 1 + 2, used for clinging to the substratum. In females, brood plates (öostegites) develop on pereonites 3 + 4. Much remains to be learnt about their biology, ecology and in many cases changing distributions.
Length: 7.7-50mm. Body smooth to very spinose, usually: one pair of dorsal head spines and lateral spines over gnathopod 2 insertions. Antenna 1 in adult males usually as long as body; antenna 2 shorter than antenna 1 peduncle. Gnathopod 1 propodus triangular, grasping margin of propodus and dactylus slightly serrate. Gnathopod 2 basis with strong antero-lateral spine; propodus slender, and with triangular projection antero-distally; palm with proximal projection bearing single spine, and with two distal projections separated by a cleft. In large adult males, both the distal cleft, and the notch distal to the grasping spine become much exaggerated. Gills elliptical. Pereopods 5 to 7 propodus bearing proximal grasping spines. Penes lateral, medially directed, and long.
May be more spinose in northern waters.
Specimens labelled as Aeginina elevata at the National Museum of Natural History, Washington DC (202150, 41m off Delaware) are missing pereopods 5-7, but otherwise are very much like Aeginina longicornis. It is not clear where the name Aeginina elevata came from and it has hence been added as a synonym.
National Museum of Natural History, Washington DC: (NMNH) 26017 Off Newport Sta. 787 USFC (A. longicornis var. nodosa) 19ftms; (NMNH) 168 Gulf of Maine; USFC 1878Loc 169;
(NMNH) 202150 labelled Aeginina elevata
Ecology and Distribution
Hudson River estuary; Atlantic Canada: Bay of Fundy, Nova Scotia, Newfoundland; Gulf of St Lawrence: Nova Scotia, Prince Edward Island, New Brunswick, Gaspé; St. Lawrence River estuary; Saguenay fjord; Arctic Canada: west to 106°20’ north to 76°46’; Greenland (W+S); Norway; Denmark; Faroe Islands; Shetland Islands; Iceland; Newfoundland to North Carolina.
<10 m to 2258 m. On algae, sea grass, hydroids, bryozoans and from the gut of the sea bass Centropristis.
Highest abundances sampled in August and September; ovigerous females absent from January to March.
Extended maternal care
Intermediate host to marine fish parasite: Echinorhynchus gadi
- Aeginella longicornis (Holmes, 1904) (synonym)
- Aeginina elevata (synonym)
- Aegina echimata (Boeck,1861) (synonym)
- Caprella scolopendroides (Ross,1826) (synonym)
- Aegina spinosissima (Sars, 1909) (synonym)
- Aegina spinifera (Rodger, 1894) (synonym)
- Caprella spinifera (Bell, 1855) (synonym)
- Aegina longicornis (Krøyer, 1842) (synonym)
- Aegina laevis (Boeck, 1861) (synonym)
- Aeginella spinosissima (Mayer, 1890) (synonym)