Most people are familiar with the flatfishes (flounders, soles etc). These fishes are very compressed, bottom-dwellers that have both eyes on the same side of the head. The larvae are also compressed, but unlike the adults, they are pelagic and have eyes on either side of the head.
The top image shows a 12 cm long larval flatfish that was sent to the Australian Museum for identification by commercial fisherman, S. Chalker of Tuncurry. The fish was found inside the gut of a Lancetfish, (probably Alepisaurus ferox Lowe, 1833) that was captured on a longline near Lord Howe Island, 700 km off the New South Wales coastline.
The fish was sent on loan to Dr A. Fukui, (School of Marine Science and Technology, Tokai University, Japan), who identified it based on fin ray counts, pigmentation and its large size. As part of his work on this fish, Dr Fukui cleared and stained the specimen (see second image). Clearing and staining involves clearing the flesh, staining the bones red and the cartilage blue. This technique is particularly useful for examining the structure of the skeleton.
The species has a wide distribution in the Indian and western Pacific Oceans.
The map below shows the Australian distribution of the species based on public sightings and specimens in Australian Museums. Click on the map for detailed information. Source: Atlas of Living Australia.
Life history cycle
Larval size of flatfishes vary greatly. The Pelican Flounder has one of the largest larvae of any flatfish. The larvae of some other flatfish species settle at as little as 1 cm in length.
Close to the time when the Pelican Flounder larva settles on the bottom, the right eye migrates to the left side of the head, the gut retracts within the abdominal cavity and the transparent body takes on a mottled appearance.
- Fukui, A. 1997. Early Ontogeny and Systematics of Bothidae, Pleuronectoidei. Bull. Mar. Sci. 60(1):192-212.
- Fukui, A. 2001. Larva of Chascanopsetta lugubris lugubris (Bothidae) disgorged by lancetfish (Alepisaurus sp.). Ichthyological Research. 48:100-103.
- Leis, J.M & T. Trnski. 1989. The Larvae of Indo-Pacific Shorefishes. NSW University Press. Pp. 371.