356 LUMINOUS ORGANISMS OF FAR EAST 



Other interesting deep sea luminous squids, such as Abralia ja- 

 ponica, Chiroteuthis, and CaUiteuthis, are obtained in shrimp nets of 

 trawlers in Suruga Bay. Appearing in particularly great numbers are 

 Chiroteuthis imperator (Japanese name, Yurei-Ika, meaning ghost 

 squid), which fishermen throw away because it has no commercial 

 value. This squid has many well-developed luminous organs on the 

 eyeballs, tentacles, and abdomen. The tentacles of large specimens 

 extend 2 meters and attached to them for some length are many lumi- 

 nous organs, like many small lamps on one thread. 



Sasaki (1915) described two new luminous oegopsids from the Bay 

 of Sagami, namely Meleagroteuthis separata and Symplectoteuthis 

 hiininosa. The luminous organs of the former are uniform in appear- 

 ance, thickly covering the ventral surface of the whole body, but are 

 found in less number on the dorsal surface. Luminous organs are 

 found also on the ventral and dorsal surfaces of the head and arms. 

 The Symplectoteuthis huninosa were taken six miles off Misaki, at 

 700 fathoms in 1906. According to Sasaki, a macula is found on the 

 ventral surface of the head. On the ventral surface of the mantle 

 there occur a pair of longitudinal zones of the same character which 

 run along the whole length of the mantle and are divided into three 

 parts. He supposed the maculae and zones to be luminous organs, 

 judging from their histological structures. 



Crustacea 



Many self-luminous species appear among the orders of Crustacea 

 in Japan. The luminous species Cypridina, belonging to the Ostracoda 

 and Heterocarpus sibogae of the Decapoda, which secrete a luminous 

 liquid, while Sergestes prehensilis of the Decapoda, with photophores, 

 and certain freshwater luminous shrimp are the most interesting and 

 remarkable. 



Cypridina 



Cypridina hilgendorfii (Japanese name, Umihotaru, meaning sea 

 firefly), shown in Fig. 7, is abundant along the coast of Japan from 

 July to September. A well-known crustacean, it is often used for 

 biochemical studies. It is 3 mm long and produces a strong lumines- 

 cent secretion. It can be preserved in a dried condition, and the 



