may take days). However, the presence 
of Calliactis forms a powerful argument 
against such attacks. In aquarium ex- 
periments, an octopus that attacks a 
guarded shell will retreat very quickly, 
as if hurt. After a few such incidents, all 
attacks cease and, in fact, the octopus 
will retreat whenever a protected crab 
approaches. 
The relationships between various 
species of Calliactis and hermit crabs 
are complex. In some cases, the anem- 
one decides when to transfer to a hermit 
crab shell, moving with some alacrity 
from site to site. In other situations the 
crab has some influence, going so far as 
to assist in removing an anemone from 
one substrate and settling it on its own 
shell. Such is the value of an anemone 
that some species of hermits steal 
anemones from other species. 
The polychaete worm Arctonoe 
vittata lives within the folds of the fleshy 
mantle of the marine intertidal keyhole 
limpet Diodora aspera. Though normal- 
ly reclusive, the worm boarder will ac- 
tively defend its mollusk host against 
starfish predators. 
Sensing a starfish, the limpet thrashes 
about with considerable verve, in what is 
known as a mantle response. Soon there- 
after — often within fifteen seconds — 
the worm sticks its head out from under 
the shell and searches about with poking 
movements. As it comes close to the 
predator, the worm’s movements quick- 
en until it touches one of the many small 
tube feet located on the starfish’s under- 
side. Once contact is made, the worm 
examines the foot with sensory palps 
located on each side of its head. Then it 
thrusts out its jaws and bites the tube 
foot, often repeatedly. Apparently, this 
is usually sufficient to cause a starfish to 
withdraw those feet that are in the lim- 
pet’s vicinity. Scientists do not know 
what stimulates the worm to come to the 
limpet’s rescue. Chemical cues emitted 
by host, predator, or both may be in- 
volved or the movement of the mantle 
may be the primary stimulus. 
The world being what it is, there will 
be those among us who will insist on a 
somewhat mechanistic view of this be- 
havior, seeing only that A. vittata has 
evolved through natural selection to de- 
fend its (limpet) territory. Ever the ro- 
mantic, however, I prefer to see an em- 
battled defender of hearth and home, 
where home is another organism. 
Greater love hath no worm. 
Milton Love is a research associate in 
the Department of Biology at Occiden- 
tal College, Los Angeles. 
'fou never forget 
your first Girl. 
