| 1a |
Apex
(located near the end of the first one-eighth) decidedly lower than the
highest part of the shell, which is near the middle; length up to 10 cm
(not often found north of California) (picture) |
Lottia
gigantea |
| 1b |
Apex
the highest
point of the shell; length rarely more than 5 cm |
2 |
| 2a |
Interior of the shell uniformly white, without an apical
blotch or marginal markings (apex
at the end of the first one-third; shell with prominent, flat radial
ribs;
length not exceeding 2 cm; associated with encrusting coralline algae
and
often coated by a bryozoan of the genus Rynchozoon;
subtidal, rare)
[Note: the anterior end of the shell can be determined by the
location
of the head, if the animal is still inside. For an empty
shell the
anterior end is the end toward which the open end of the C-shaped
mantle
scar on the inside of the shell points] |
Niveotectura funiculata |
| 2b |
Interior of shell not uniformly white (it may be
uniformly dark or
have markings, such as an apical
blotch, marginal band, or marginal streaks or spots) |
3 |
| 3a |
Right and left margins of the shell nearly parallel for
much of their
length (photo),
the outline of the
aperture
thus somewhat elongated |
4 |
| 3b |
Right and left margins of the shell curving outward,
the outline of
the shell thus oval (a form of Lottia
pelta
that lives on the kelp
Egregia, and forms of L.
pelta and L. ochracea that live
on stipes of laminarians,
may also have nearly parallel margins; see choices 4a and 7a) |
8 |
| 4a |
Right and left margins lower than the anterior and
posterior margins
(photo),
so the shell can
be rocked when it is on a flat surface (on stipes of laminarian kelps,
such as Pterygophora, to which it clings after the
fashion of a
saddle; length up to about 2 (3.5) cm; shell
brown). Caution:
forms of Lottia pelta
and
L.
ochracea also occur on the stipes of laminarians, and the
shape of
their shells may resemble that of this species; as a rule, however,
they
are not predominantly brown) |
Lottia
instabilis |
| 4b |
Right and left margins at essentially the same
horizontal level as
the anterior and posterior margins, so the shell has little tendency to
rock when on a flat surface |
5 |
| 5a |
Length about 4 times the width; apex
near the end of the first quarter (restricted to the leaves of Phyllospadix;
shell brown; lenth up to about 8 mm) |
Tectura paleacea |
| 5b |
Length not more than 3 times the width; apex
near the end of the first third or closer to the middle |
6 |
| 6a |
Length about 3 times the width (exterior of shell
mostly whitish, but
with brown radial markings and sometimes witha brown spot at the apex;
on coralline red algae; length up to about 8 mm; rare) |
Lottia triangularis |
| 6b |
Length not more than twice the width |
7 |
| 7a |
Exterior and interior of shell dark brown; length up to
2 cm; on the
kep Egregia (picture),
whose stipes it erodes (height about three-fourths the width) |
Discurria
insessa |
| 7b |
Exterior of shell mostly dark brown, but with light
markings (these
are more or less radial or contribute to a checkerboard pattern),
interior
bluish, with a brown apical
stain and with external markings showing through; length up to 1.2 cm;
on leaves of eelgrass, Zostera marina (not likely
to be found south
of Washington) |
Lottia
alveus |
| 8a |
Exterior of shell mostly pink, with white and/or light
brown markings
(length up to about 8 mm; on coralline red algae; subtidal, rare) |
Tectura rosacea |
| 8b |
Exterior of shell not mostly pink, unless overgrown by
coralline red
algae |
9 |
| 9a |
Exterior of shell mostly whitish, but with brown radial
markings and
a brown spot at the apex;
apex
nearly in the middle; on coralline red algae; length up to about 8 mm
(rare) |
Lottia triangularis |
| 9b |
Exterior of shell not mostly whitish (unless encrusted
by a coralline
alga that becomes white), with or without markings, but not typically
with
a brown spot at the apex;
apex
usually decidely anterior to the middle; except for Lottia
painei
and a form of L. ochracea, not generally on
coralline red algae;
length commonly more that 1 cm, except in Lottia asmi
(includes
most of the interidal and shallow subtidal limpets) |
10 |
| 10a |
Shell grayish or brownish black externally, uniformly
black internally;
length not often more than 1 cm; mostly on Tegula
funebralis, sometimes on Mytilus
californianus, rarely on rock |
Lottia
asmi |
| 10b |
Color not uniformly black internally, although the
exterior may be
mostly dark; length commonly more that 1 cm, except in Lottia
ochracea;
except for some small L.
pelta,
not likely to be found on Tegula
funebralis (large L. pelta,
however, occur on Mytilus
californianus) |
11 |
| 11a |
Shell with prominent ribs radiating from the apex
to the margin |
12 |
| 11b |
Shell without prominent ribs radiating from the apex
to the margin (if there are ribs, they are delicate and closely spaced) |
15 |
| 12a |
Apex
anterior
to the end of the first quarter, and sometimes nearly level with the
anterior
margin; radial ribs more prominent posterior to the apex
than anterior to it (common high intertidal species) |
Lottia
digitalis |
| 12b |
Apex
at about
the end of the first quarter or first third; ribs anterior to the apex
about as well developed as those posterior to it |
13 |
| 13a |
Height generally about one-fourth of the length (but
sometimes more
than one-fourth); margins prominently scalloped (the places where the
radial
ribs meet the margin may project as points) (length up to 3 cm; animal
white, with dark spots on the sides of the foot; generally in
depressions
in rock, to which the animals return after foraging; not likely to be
found
north of Oregon) |
Family Nacellidae:
Macclintockia scabra |
| 13b |
Height generally more than one-fourth of the length ;
margins not prominently
scalloped (the places where radial ribs meet the margin are rounded and
do not project as points) |
14 |
| 14a |
Ribs with overlapping scales, thus rough to the touch |
Lottia limatula |
| 14b |
Ribs without overlapping scales, not rough to the touch |
Lottia
pelta |
| 15a |
Length usually not more than 1.3 times the width |
16 |
| 15b |
Length usually at least slightly more than 1.3 times
the width |
17 |
| 16a |
Height usually not more than one-third the width;
exterior usually
with a pattern of light and dark streaks or blotches; length sometimes
exceeding 5 cm (common mid- and low intertidal and shallow subtidal
species) |
Tectura
scutum |
| 16b |
Height usually more than one-third the width, exterior
mostly uniformly
brown, olive, or gray, but sometimes with a few white spots; length not
often exceeding 3 cm (mostly on smooth boulders and rocks in the mid-
and
low intertidal) |
Tectura
fenestrata |
| 17a |
Shell thin, translucent; coloration of exterior
resembling a checkerboard
of white and dark (usually brownish or reddish) markings (these show
through
to the interior) (length up to about 1 cm) |
Lottia ochracea |
| 17b |
Not generally thin or translucent except in young
specimens; coloration
of exterior sometimes with light spots and light and dark radial
streaks,
but not resembling a checkerboard |
18 |
| 18a |
Interior of shell white or faintly bluish, with a
continuous dark border,
or with a border of dark spots, but without a blotch at the apex
(exterior of shell often so badly pitted by a fungus that it is
uniformly
dull gray; length not often more than 1.5 cm; mostly mid-intertidal) |
Lottia strigatella |
| 18b |
Interior of shell with a blotch at the apex
(in Lottia painei, however, the blotch is small and
faint) |
19 |
| 19a |
Apical
blotch
on interior of shell large, dark brown; margin of interior with a
continuous
dark band; shell length commonly exceeding 3 cm; not regularly
associated
with coralline red algae or encrusted by an alga of this type |
20 |
| 19b |
Apical
blotch
on interior of shell small, faint, grayish, margin of interior with
short,
nearly radial streaks, or with both streaks and a narrow band; shell
length
rarely exceeding 2 cm; associated with coralline red algae and
typically
encrusted by an alga of this type |
Lottia painei |
| 20a |
Apex
at the
end of the first one-third, often inclined slightly forward; posterior
and lateral slopes of shell markedly convex; lateral margins of shell
often
slightly higher than the anterior and posterior margins, so that the
shell
can be rocked from side to side when placed on a flat surface; apical
blotch usually at least half the length of the shell; length up to
about
5 cm; at higher levels of the intertidal region, and mostly at the
edges
of the undersides of boulders, except when foraging. |
Tectura
persona |
| 20b |
Apex
slightly
behind the end of the first one-third, not often inclined forward;
posterior
and lateral slopes of the shell slightly if at all convex; lateral
margins
of the shell usually at the same horizontal level as the anterior and
posterior
margins; apicalblotch
usually about one-third the length of the shell; length up to about 4
cj;
mostly mid- and low intertidal |
Lottia
pelta |
