Senticaudata Lowry & Myers 2013

These are tube dwelling, nonnative amphipods introduced into harbors by shipping. Adult males, such as this one, leave the safety of their tube to cruise about in search of a receptive female.

Figure 2.Photograph of live specimen of Zenkevitchia yakovi sp. n. in the cave “Istočnik Tcebel’da”, from right side. Photography by A. Korotaev.

Figure 1.Elasmopus yucalpeten sp. n., holotype male, 6.6 mm, CYMX-1-EY; Yucalpeten harbor, Yucatan, Mexico. Scale bar for H represents 1 mm; scale bars for G1 and G2 represent 0.3 mm; scale bars for AF and T represent 0.1 mm.

Figure 2.Niphargus plurispinosus sp. n.: 1 male, general view; 1a-1b dorso-later thorns; mdb - mandibula and details of mdb-a left incisor and lacina mobilis; mdb-b) two setae between bisserated thorns; mdb-c setae pattern on distal segment of mdb-palp; mdb-d, right incisor and lacina mobilis; mx-1 1st maxilla; mx-2 2nd maxilla; ula upper lip; vela ventral labium; mxp maxilliped: in inner segment os outer segment; ds distal segment of palp; epI-epIII epimeral plate I-III; A-I 1st antenna; A-II antenna; hc head capsula, left lateral view; telson, dorsal view. Not scaled, except of the general view of the male.

This individual is digging in under beach wrack (stranded algae) in the early morning hours. Several other amphipods have dug in nearby. Photo from Shi Shi Beach by Dave Cowles, July 2008 This individual is heading down a typical burrow which it has just dug. Photo from Shi Shi beach by Dave Cowles, July 2008

This view shows the same individual from the dorsal aspect.

Sand hopper; strandvlo.

Caprella kennerlyi posteriorCaprella kennerlyi posteriorSpecimens from: National Museum of Natural History, Washington DC: (NMNH) 25950

Figure 3.Niphargus plurispinosus sp. n.: 1 upper lip 2 right mandible 3 second maxilla 4 labium 5 half maxilliped (without inner portion) 6 3rd uropod (female) 7 3rd uropod (juvenile male) 8–9 telson (one lobe of male) 10 2nd gnathopod 11 4nd pereopod 12 7th pereopod 13 distal segment and 6th pereopod 14 6th pereopod: regeneration of segments behind basis (Photo: I. Hudec). Not drawn to scale.

Generally Megalorchestia californiana beachhoppers are out feeding at night and dig burrows to stay in during the day. I have seen many of their burrows underneath kelp high on the beach (see photos above). This view shows an unusual set of Megalorchestia californiana burrows at Shi Shi beach. The burrows are on a high brow of dry sand, just above a steep sand bank that drops to the lower beach. The photo is taken shortly after dawn. The night high tide came up and sculpted the sand bank but did not reach quite this far. When I passed by the area was covered with many Megalorchestia calforniana, some still walking around but most digging these characteristic, cone-like burrows. Each hole between the two pyramid-like mounds contains a beachhopper facing head-down and kicking sand up onto the mounds. The photo is looking directly away from the ocean so most of the beachhoppers were orienting themselves to the left and right on the beach whle they dug. Photo by Dave Cowles, late July 2008

In this ventral view of the anterior half of the body, the gnathopods present at the anterior end of pereonite 1 and at the posterior end of pereonite 2 are visible. It has no gills on either of these pereonites.

Caprella linearis;

Caprella kennerlyi anteriorCaprella kennerlyi anteriorSpecimens from: National Museum of Natural History, Washington DC: (NMNH) 25950

Figure 4.Zenkevitchia yakovi sp. n.: holotype, male (10.0 mm), X43382/Cr-1613-FEFU. A Head, lateral view B, C Antenna 1 and 2, lateral views D Labium, ventral view E Labrum, anterior view F, G Left and right mandibles, medial views H Epimeral plates 1–3, lateral views I pleopod 2, medial view J Coupling setae (retinacula), medial view.

Figure 3.Elasmopus yucalpeten sp. n., holotype male, 6.6 mm, CYMX-1-EY; Yucalpeten harbor, Yucatan, Mexico. Scale bars represent 0.3 mm.

Figure 4.Niphargus plurispinosus sp. n. – “postreproductive” male: 1 gnathopods with detail of deformed gpI (1a) and normal developed gpII (1a) 2 gpII -setae on dactylus 3 telson and regenerated (?) upIII 4 segment setae on flagellum of AI 5 maxillae I: position of three setae on inner portion (Photo: I. Hudec). Not drawn to scale.

Megalorchestia californiana near decaying kelp on the high intertidal beach of Mukkaw Bay at dusk. Body length about 2 cm. Note how large this species is compared to the other amphipod seen behind it. (Photo by: Dave Cowles, July 2008)

In this ventral view of the posterior half of the body (head is to right), the flat leaflike gills can be seen on midsections of pereonites 3 and 4 (part of the second gnathopods can be seen at the right on pereonite 2). Ahead of each gill is a small bump which is the vestigial pereopod for that pereonite. Pereonites 5-7 on the left have well-developed pereopods which act as claws to attach the animal to the eelgrass.

Gammarid; Vlokreeftje.

Caprella kennerlyi anteriorCaprella kennerlyi anteriorSpecimens from: National Museum of Natural History, Washington DC: (NMNH) 25950