Sepioteuthis

GPO87

Sepia elegans
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These loliginids are commonly known as the reef-squid. They have fins that run most of the length of the mantle. They are commonly found around reefs in shallow waters (hence the name). They grow to a moderate size, growing up to around 20 cm mantle length.


Sepioteuthis lessoniana

Sepioteuthis
 

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Phylogeography of Sepioteuthis lessoniana and Uroteuthis duvauceli 2013
A thesis submitted to the University Honors Program in partial fulfillment of the requirements for the Honors Degree Southern Illinois University April 18, 2013

Abstract
Sepioteuthis lessoniana (the bigfin reef squid) and Uroteuthis duvauceli (the Indian squid) are two squid species found in largely overlapping regions in the Indian and Pacific Oceans. While both squids are important to fisheries throughout their ranges, very little taxonomic work has been done on either of them. Previous studies have led scientists to believe that S. lessoniana is actually a species complex (for example, there appear to be three species of “S. cf. lessoniana” in Japanese waters alone). The similarly broad geographic range of U. duvauceli suggests that this species could also harbor substantial cryptic genetic diversity. In order to evaluate genetic
variation within these two species, regions of two mitochondrial genes—the large subunit ribosomal RNA gene (16S) and the cytochrome oxidase I gene (COI)—from specimens caught in regions throughout the northern Indian and western Pacific Oceans were sequenced and
compared. Sequences were obtained by extracting the DNA from tissue samples of both species, amplifying the DNA using the polymerase chain reaction (PCR), determining the sequences of both DNA strands using a automated DNA sequencer, and comparing sequences to one another to establish similarities and differences between geographic locations. To expand the significance of this study, we compared our sequences to data contributed by a collaborator (Samantha H. Cheng, Department of Ecology and Evolutionary Biology, UCLA) and data
downloaded from GenBank (an online genetic database). Phylogeographic analyses showed that Sepioteuthis lessoniana from southern India represent two very distinct genetic lineages, suggesting that “S. cf. lessoniana” comprises at least two cryptic species in south Indian waters. For Uroteuthis duvauceli, specimens from Iran are genetically distinct from those in Thailand and Japan, which may support the hypothesis of several undescribed species within “U. cf. duvauceli”. This study is the first attempt to assess genetic diversity across the ranges of these two species; future work will require additional genetic markers and (most importantly) additional sampling from other geographic regions.
 
Zoologger: Squid snares prey using badly blurred vision

Species: Sepioteuthis lessoniana

Habitat: bobbing up and down around inshore coral reefs of the Pacific and Indian Oceans

The hunter closes in on its prey. The victim, a small and nondescript prawn, is puttering about in open water above a coral reef. The eyes of its predator, a bigfin reef squid, are locked upon it.

Then the squid starts to bob up and down, as if on an invisible trampoline. Moving forward, it suddenly lashes out with its tentacles and ensnares the hapless prawn.

The bobbing behaviour seems completely counterproductive: surely it attracts the prawn's attention? In fact, it's the only way the squid can tell how far away the prawn is.
...

... "The animal has a built-in rangefinder tuned to its body size and strike length," says Marshall. ...
 

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