80 THE ESSEX NATURALIST.
All ephyrae are cannibals when young. Aurelia may easily
be grown up to 2 inches in diameter on Dendrobaena (garden
worm) in a 2lb. jam jar; ephyrae grown on this food and in that
manner turned out to be as fine little medusae as others from
the same stock which were sent down to Plymouth and which
were fed on plankton there. If one chose to concentrate on
Aurelia alone and to keep them in large containers it should
be possible to grow them much larger, but normal summer
air-temperatures are too high for them to prosper, usually,
in artificial conditions.
Chrysaora can also be raised easily on garden worm up to-
one-third of an inch. Beyond that size Ctenophores must be
supplied, or at least other jellyfish, if the bell is to develop;
otherwise the bell does not grow, though the other parts do, and
the creatures languish miserably on the bottom. One will realise
that away from the sea it is usually hopeless to attempt the
rearing of Chrysaora. I attempted to feed Chrysaora ephyrae
once on undeveloped and motionless ova-planulae from Cyanea.
The planulae remained undigested within the body-cavity of the
ephyrae and developed and grew; moving about they apparently
choked the entrances to the diverticulae and all the ephyrae
perished miserably. Needless to say I did not give this food
again.
The ephyrae of Chrysaora are very voracious and given suitable
food develop rapidly, up to an air-temperature of 80o Fahr.
Cyanea ephyrae are most difficult to rear. Though belonging
to a group inhabiting very cold water, I found that at low tem-
peratures they would not eat, but in their case my difficulties
may have been partly due to lack of oxygenation of the water.
With young forms of medusae it is very important to avoid free
air bubbles in the water since they tend to pass into the body
cavity of the creatures and to form a large air-pocket which often
works into the diverticulae, renders them absolutely helpless,
and sometimes destroys them. I shall not forget my struggles
to rear Cyanea solus in 1932. Back from duty at 7 p.m., a hasty
meal, and then off to the pier (one hour's journey away) to
catch the tide at the psychological two hours during which,
alone, it was possible to obtain anthoid medusae brought by
the tide from Whitstable and "the Land" (Sheppey), with a
drift net. Then followed the search at midnight for these small