264
J. H. S. BLAXTER AND F. 0. T. HOLLIDAY
following in tracing literature: Dr. Vivien Brawn (Vancouver), Mr. J.
Jakobsson (Reykjavik), Dr. R. Lasker (La Jolla), Dr. Radosna Muiini6
(Split), Prof. G. Nikolsky (Moscow), Dr. P. A. Orkin (Aberdeen) and
Dr. C. J. Sindermann (Boothbay Harbor). Dr. Z. Kabata (Aberdeen)
has assisted greatly in translating Russian papers.
Thanks are due to Mr. B. B. I’arrish (Abcrdeen) and Dr. G. Hempel
(Hamburg) who read and criticized this paper in manuscript, and to
Dr. G. Krefft (Hamburg) for his advice on nomenclature.
B. Characteristics of Clupeids
The Clupeidae are to be found in all habitats from fresh water,
txg. some Pomolobus and Harengula species, to sea water. Many of them
are anadronious such as Alosa, Caspiolosa and Pornolobus. The family
contains species which lay demersal eggs offshore (herring) , demersal
eggs in shallow water (Clupea p a l h i i ) and pelagic eggs (Surdinope).
Hatching takes place in a few days (the eggs being small) and there
is little yolk available before the larva must find an external source of
food. These larvae are usually very small and transparent, metamorphosing after some months to the adult form. The larvae and
juveniles of marine species are often found on shallow inshore nursery
grounds.
Thc fccundity is low compared with many teleosts, but the numbers
of individuals arc high. The adults of most species adopt a pelagic and
shoaling habit and often make extensive migrations for feeding and
spawning. They arc mostly plankton and therefore seasonal feeders,
laying down fat reserves which allow them to survive when food is
scarce. Lacking much in the way of defence mechaniams, except pratective colouration, speed and shoaling, and being present in such large
numbers, most clupeids are heavily preyed upon by other fish, mrtmmals and birds.
11. THE GAMETES
A. Basic structure and composition
1. The sperm
The morphology of herring sperm has been studied by Retzius (1906)
and Ballowitz (1915) who described the successive stages in the tranaformation from spermatid to spermatozoon by the development of the
tail piece. It is unlikely that the sperm of other clupeid8 differs significantly from that of the herring.
The head is compoRed almoHt cntircly of nuclear material and In
approximately 1p in diamotor; R short middlo picco i~ followod by a
J. H. S. BLAXTER AND F. 0. T. HOLLIDAY
following in tracing literature: Dr. Vivien Brawn (Vancouver), Mr. J.
Jakobsson (Reykjavik), Dr. R. Lasker (La Jolla), Dr. Radosna Muiini6
(Split), Prof. G. Nikolsky (Moscow), Dr. P. A. Orkin (Aberdeen) and
Dr. C. J. Sindermann (Boothbay Harbor). Dr. Z. Kabata (Aberdeen)
has assisted greatly in translating Russian papers.
Thanks are due to Mr. B. B. I’arrish (Abcrdeen) and Dr. G. Hempel
(Hamburg) who read and criticized this paper in manuscript, and to
Dr. G. Krefft (Hamburg) for his advice on nomenclature.
B. Characteristics of Clupeids
The Clupeidae are to be found in all habitats from fresh water,
txg. some Pomolobus and Harengula species, to sea water. Many of them
are anadronious such as Alosa, Caspiolosa and Pornolobus. The family
contains species which lay demersal eggs offshore (herring) , demersal
eggs in shallow water (Clupea p a l h i i ) and pelagic eggs (Surdinope).
Hatching takes place in a few days (the eggs being small) and there
is little yolk available before the larva must find an external source of
food. These larvae are usually very small and transparent, metamorphosing after some months to the adult form. The larvae and
juveniles of marine species are often found on shallow inshore nursery
grounds.
Thc fccundity is low compared with many teleosts, but the numbers
of individuals arc high. The adults of most species adopt a pelagic and
shoaling habit and often make extensive migrations for feeding and
spawning. They arc mostly plankton and therefore seasonal feeders,
laying down fat reserves which allow them to survive when food is
scarce. Lacking much in the way of defence mechaniams, except pratective colouration, speed and shoaling, and being present in such large
numbers, most clupeids are heavily preyed upon by other fish, mrtmmals and birds.
11. THE GAMETES
A. Basic structure and composition
1. The sperm
The morphology of herring sperm has been studied by Retzius (1906)
and Ballowitz (1915) who described the successive stages in the tranaformation from spermatid to spermatozoon by the development of the
tail piece. It is unlikely that the sperm of other clupeid8 differs significantly from that of the herring.
The head is compoRed almoHt cntircly of nuclear material and In
approximately 1p in diamotor; R short middlo picco i~ followod by a