Chemical defense in pelagic octopus paralarvae: Tetrodotoxin alone does not protect individual paralarvae of the greater blue-ringed octopus (Hapalochlaena lunulata) from common reef predators

Abstract

Some pelagic marine larvae possess anti-predator chemical defenses. Occasionally, toxic adults imbue their young with their own defensive cocktails. We examined paralarvae of the greater blue-ringed octopus (Hapalochlaena lunulata) for the deadly neurotoxin tetrodotoxin (TTX), and if present, whether TTX conferred protection to individual paralarvae. Paralarvae of H. lunulata possessed 150 ± 17 ng TTX each. These paralarvae appeared distasteful to a variety of fish and stomatopod predators, yet food items spiked with 200 ng TTX were readily consumed by predators. We conclude that TTX alone does not confer individual protection to paralarvae of H. lunulata, and that they possess an alternative defense. In larger doses, tetrodotoxin is a deterrent to the predatory stomatopod Haptosquilla trispinosa (mean dose = 3.97 lg/g). This corresponds to 12-13 paralarvae per predator based on the TTX levels of the clutch we examined. Thus, the basic assumption that individual paralarvae of H. lunulata are defended by TTX alone was disproved. Instead, functionality of TTX levels in paralarvae may arise through alternative selective pathways, such as deterrence to parasites, through kin selection, or against predator species not tested here.

Including planocerid flatworms in the diet effectively toxifies the pufferfish, Takifugu niphobles

“…TTX in the offspring of toxic organisms such as pufferfish, octopus, newt and flatworm, appear to be obtained by means of a vertical maternal transfer 34 – 39 . This maternally provided TTX provides even just-hatched larvae protection from predators 34 , 35 .…”

Guidelines for the Care and Welfare of Cephalopods in Research –A consensus based on an initiative by CephRes, FELASA and the Boyd Group

“…467,468 The toxin involved is the potent sodium channel blocker TTX 469 that is found in the posterior salivary glands, skin, branchial hearts, gills and Needham’s sac, 470 so care should also be taken with handling these animals post mortem . Recently, TTX has been found in the eggs with the levels increasing after laying; 471 therefore, the risk with this species does not only come from adults. Other data show that the venom is produced by symbiotic bacteria ( Aeromonas , Bacillus , Pseudomonas and Vibrio ) found in the salivary glands.…”

Death in the octopus’ garden: fatal blue-lined octopus envenomations of adult green sea turtles

“…The lack of distinct puncture marks may also be an indication that the octopus may not have bitten the inner tissue of the esophagus; instead, toxins may have been leached from the dermis of H. fasciata , as proposed by Yotsu-Yamashita et al ( 2007 ). However, while TTX has been detected in high levels in multiple regions of the octopus body (Yotsu-Yamashita et al 2007 ; Williams and Caldwell 2009 ; Williams et al 2011 ), it has been shown that the consumption of tissue is fifty times less toxic relative to intraperitoneal injection (Xu et al 2003 ). The lack of detectable TTX in the seagrass bolus in which the octopus was fully encased further indicates that the TTX detected in the turtle tissues came from the octopus via active envenomation, not exudation.…”

“…This powerful technique utilizing HPLC–MS with hydrophilic interaction chromatography was chosen above single-stage mass spectrometry (SSMS). During SSMS, many other substances may elute off the column at the same retention time as TTX, making a negative control necessary (Matsumura 1995 , 2001 ; Williams et al 2004 , 2011 ). To highlight the strength of this technique, we included a negative control, although it was unnecessary as the technique provides unequivocal identification of TTX.…”

“…TTX has been shown to have a wholly lethal dose (LD) of 5.8 μg/kg via intramuscular injection (Xu et al 2003 ), and it is estimated that a tiny 25 g octopus possesses enough venom to fatally paralyze ten 75 kg humans (Narahashi et al 1967 ; Sutherland 1983 ; Williamson 1987 ). While there are high levels of TTX in many of the tissues of H. fasciata , including their arms and mantel (see Yotsu-Yamashita et al 2007 ; Williams and Caldwell 2009 ; Williams et al 2011 ), there is currently no empirical evidence that the octopuses can exude TTX from these tissues. Instead, envenomation is thought to occur through subcutaneous injection via a bite from its small, parrot-like beak (Edmonds 1969 ; Yotsu-Yamashita et al 2007 ).…”