Californian Beach Hoppers — B owers 
317 
pushed up less vigorously than by calif orniana 
and thus simply falls all around the burrow 
mouth in a rounded heap. Large individuals are 
usually found with smaller animals in mid- to 
high-tide zones rather than higher up on drier 
parts of the beach, as in calif orniana. The bur- 
rows are commonly open just around the hopper 
and are usually less than 6 inches deep, but I 
have found these hoppers more than 2 ft down. 
The three smaller hopper species dig less 
than the large hoppers and thus do not make 
very obvious surface markings. They are more 
often found associated with washed-up debris. 
I have found no sexual dimorphism with re- 
spect to pigmentation pattern, but the sex of 
these animals is easily distinguished by the 
structure of the 2nd gnathopods (the 2nd pair 
of large ventral appendages) except as noted 
below (see Fig. 1). In females the sixth seg- 
ment is a fleshy paddle-shaped structure. In 
young genetic males the same form is present, 
but it becomes modelled through a series of 
molts into a larger subchelate "hand” with a 
curved dactyl closing against an emminence of 
the "palm.” As far as I know, males can be dis- 
tinguished from females only when the change 
in the gnathopods begins to be apparent. In 
calif orniana and corniculata this occurs when the 
animals reach about 9.0 and 13-0 mm in body 
length, respectively (measured from the anterior 
of the head through the chord of the straight- 
ened but still somewhat curved body to the 
back edge of the 3rd abdominal segment ) . Sex- 
ually active females possess oostegites under the 
thoracic region. These are thin plates with a 
fringe of hairs, which overlap to form a mar- 
supium in which eggs and young are carried. 
However, some large females lack these hairs, 
their presence apparently being dependent on 
the breeding cycle rather than on size. The 2nd 
antennae of females of all species are shorter 
and less robust than those of males, and are less 
colorful. 
In midday, as the waves of a rising tide 
moisten a beach, it is common to see small ani- 
mals moving around in the just-wet area, feeding 
on fresh bits of seaweed, washed up sand crabs, 
or seemingly just wandering. Probably all species 
do this, but in my experience this movement 
has occurred mostly with columhiana, less fre- 
Fig. 2. Left 2nd antenna of O. corniculata male. 
Compare this with appendage in Figure 1. 
quently with calif orniana. Under such condi- 
tions, an observer lying face down on the sand 
can use pigmentation patterns to distinguish the 
animals without even touching them. 
The most obvious character that distinguishes 
large male calif orniana from male corniculata is 
the form and color of the second antennae. In 
calif orniana the flagellum of the antenna is rela- 
tively thin, longer than the combined length of 
the segments of the peduncle, and gradually 
tapers to the tip, which reaches back beyond the 
middle of the body when folded from the pe- 
duncle base. The color of the peduncle is usually 
rosy-red. The peduncle segments are longer but 
not as massive as those of corniculata. In cornic- 
ulata the flagellum of the antenna is thicker than 
in calif orniana, is shorter than the combined 
length of the peduncle segments, and tapers 
rapidly to the tip, which does not reach the 
middle of the body when folded ( see Fig. 2 ) . 
The color is usually salmon-pink, but sometimes, 
on a darker substrate, may be tinged with blue 
or brown. Newly molted individuals of both 
species may be white. 
The antennae of columhiana are calif orniana- 
like, but in large animals are bluish-white rather 
than red. The antennae of pugettensis are cor- 
