Food Habits of Aplysia — Winkler and Dawson 
103 
TABLE 1 
Diet of Young Aplysia calif omica at Lunada Bay 
KINDS OF PLANTS* 
NO. 
SPECIMENS 
IN WHICH 
FOUND 
NO. 
SPECIMENS 
IN WHICH 
DOMINANT 
Acrosorium uncinatum 
1 
1 
Centroceras clavulatum 
8 
4 
Ceramium eatonianum 
21 
14 
Corallina vancouveriensis 
12 
1 
Gelidium coulteri 
11 
2 
G. crinale (?) 
7 
1 
Gelidium sp. 
1 
0 
Gigartina canaliculata 
14 
7 
Hypnea valentiae 
4 
2 
Lophosiphonia sp. 
1 
0 
Phyllospadix sp. 
6 
0 
Plocamium pacifcum 
12 
2 
Pterocladia sp. 
4 
0 
Pterosiphonia sp. 
2 
0 
S per moth amnion snyderae 
1 
0 
Sphacelaria sp. 
2 
0 
Ulva sp. 
2 
0 
* Although marked differences in the relative abundances of 
the various algae in the habitat would seem to negate the 
validity of this table in indicating selectivity of food by the 
sea hares, there is some interesting supporting evidence. Al- 
though Gigartina canaliculata was the dominant intertidal 
rock-cover alga throughout the area, and was eaten, it appeared 
far less dominant in the pellets than the small, relatively in- 
conspicuous epiphytic alga Ceramium. Similarly, although 
Ulva and Plocamium were so sparse in the areas as generally 
to go unnoticed, these, especially the latter, appeared in the 
pellets. 
to be common, though never found in the fecal 
pellets: Laurencia splendens, Chondria calif orn- 
ica, Gigartina leptorhynchos, Prionitis lanceo- 
lata, Laurencia subopposita, Cystoseira osmun- 
dacea, Gymnogongrus leptophyllus, Bossea or- 
bigniana, Herposiphonia sp., Rhodymenia sp., 
and Colpomenia sinuosa. 
All specimens taken from deeper water in 
Lunada Bay and off Palos Verdes Point were 
similar in the algal content of their pellets. In 
every case the dominant plant was Plocamium 
pacificum, but with some admixture. These ad- 
mixtures included Phyllospadix sp., Lophosiph- 
onia sp., Gelidium (several species), and Cer- 
amium eatonianum . 
In May 1961 the larger red-striped A. cali- 
fornica from Lunada Bay were found feeding 
exclusively on the red alga Laurencia pacifica, 
which turned their blood and digestive glands 
a deep red. 
Observations of the crop contents of several 
hundred Aplysia specimens were made during 
the course of work in 1959 at the Lunada Bay 
lagoon. Occasional spot checks were made in 
which the contents were determined as to 
species, but no single alga was recognized as 
dominant. The samples contained: Chondria 
calif omica, Lithothrix aspergillum, Ceramium 
eatonianum, Centroceras clavulatum, Plocamium 
pacifcum, Corallina gracillus, and Ecto carpus 
sp., intermixed with fragments of coralline al- 
gae. The flora of this small lagoon contained 
more coralline algae and much less Gigartina 
canaliculata than the afore-mentioned 1955 col- 
lection site located Vy mile to the south on 
Lunada Bay. 
The collecting area at Doheny Beach was 
located at the extreme north end of the state 
park, where a small lagoon of uniformly shal- 
low water is protected on the north by a strati- 
fied rocky peninsula submerged at higher tides, 
and on the south by a wave-formed reef of 
small boulders and gravel. The flora was com- 
paratively limited, consisting predominately of 
various jointed coralline algae with intertwined 
Hypnea valentiae. Algal growth improved as 
one moved to the seaweed area of the lagoon. In 
this habitat 86 specimens were collected, but 
because of apparently grossly similar crop con- 
tents only 8 specimens were analyzed for pre- 
sentation in Table 2. Collection dates were 
March 24, 1959, for numbers D-02 to D-08, 
and April 29, 1959, for the remainder. It will 
be noted that the latter collection shows a 
greater specialization of diet than the former 
and may reflect the concentration of sea hares 
farther out in the lagoon than at the former 
collection date. It may, on the other hand, sug- 
gest that the sea hare tends to become more 
selective in its food as it becomes older. This 
has generally been noted from other areas. 
The algal contents of crops of Aplysia vac- 
caria have also been examined. Animals col- 
lected in their usual haunts in the Egregia beds 
have contained only large amounts of Egregia 
in their crops. On the other hand, when the 
animals are inshore in breeding aggregations 
the crops are usually empty or contain sand or 
other material of little significance. On one oc- 
casion only, several such animals were found 
