Lusitanian toadfish sings to keep intruders away


This video is about a Lusitanian toadfish and other fish.

From New Scientist:

Zoologger: Bagpiper fish keeps intruders away with song

15:52 01 April 2015 by Mary Bates

Species: The Lusitanian toadfish (Halobatrachus didactylus)

Habitat: Bottom-dwelling, in rock crevices or muddy sediments on the floor of the Atlantic ocean and Mediterranean sea

It whistles, grunts and croaks. The Lusitanian toadfish is quite musical for a fish. It makes at least five kinds of calls, and males even sing in choruses to attract mates with their boatwhistles – long, rhythmical, tonal sounds.

Now it seems the boatwhistle has another function: keeping intruding males away. Lusitanian toadfish can reach over half a metre in length and weigh over 2 kilograms. They have large, flat heads and wide mouths, giving them the toad-like appearance that they’re named after.

During the mating season, from May to July, males create nests under rocks and then sing to attract females. Males are territorial and they defend their nests from intruders. After mating, females leave their sticky eggs in the nest for the male to care for until the young are old enough to fend for themselves, at about three to four weeks.

Although boatwhistles were already thought to act as a keep-out signal to other males, there was no direct evidence of this. So Clara Amorim, from ISPA University Institute in Portugal and her colleagues decided to test this hypothesis by muting male toadfish and seeing what happened.

Shushing a noisy fish

Lusitanian toadfish call by contracting muscles on their swim bladders, which releases air. Different sounds result from different contraction rates. Think of it as an underwater bagpiper.

Amorim and her colleagues muted some toadfishes by cutting and deflating their swim bladders under anaesthesia. These fish could still contract their muscles, but couldn’t make any sound.

They found that the nests of muted males were more likely to be intruded upon, probably because they were unable to sing. Their results suggest that boatwhistles are effective keep-out signals, reducing the risk of territorial intrusions and therefore nest takeovers.

“Boatwhistles are a cheap way to exclude intruders without engaging in a fight,” says Amorim. “Seeing that a nest is occupied is not as effective as hearing that there is a male in the nest eager to defend its territory.”

Some aspects of toadfish boatwhistles, such as frequency and pulse interval, are associated with the size of the fish, meaning that others can use it to assess the quality of potential mates or the fighting ability of rivals.

The Lusitanian toadfish is not unique in making underwater noise. Herrings fart to find each other in the dark, clown fish chatter by clacking their jaws together to warn intruders to stay away and another species of toadfish cries like a baby.

Journal reference: Journal of Experimental Biology, DOI: 10.1242/jeb.116673

Giant manta ray at play, video


This video, recorded off Peru, says about itself:

Curious giant manta ray surprises manta researcher! The manta researcher was collecting a photo ID, used to monitor population trends that can help identify the effects of fishing pressure on this population of manta rays.

Full story here.

See also here.

Great Barrier Reef fish conservation works


This video from Australia says about itself:

Coral trout, Plectropomus leopardus, gather to spawn at dusk around the new moon in spring and early summer at Lizard Island on the northern Great Barrier Reef. Substantial research into the biology and ecology of this highly sought-after table fish has been conducted at the Australian Museum‘s Lizard Island Research Station.

From Science News:

No-fishing scheme in Great Barrier Reef succeeds with valuable fishes

Coral trout thrive but protection has less effect on other reef residents

By Susan Milius

12:15pm, March 26, 2015

An ambitious, hotly debated system of no-take reserves inside the Great Barrier Reef Marine Park has boosted the population of its most commercially valuable fishes, says the first 10-year progress report.

Coral trout (Plectropomus species) are now more common and bigger in protected spots than in comparable places still being fished, researchers say online March 26 in Current Biology. The no-take zones also gave these fish populations more resilience, with ample coral trout that had grown large enough to survive when severe tropical cyclone Hamish hit in 2009.

Freshwater sculpin taking care of eggs, video


This video from the Netherlands says about itself (translated):

Jos van Zijl filmed this freshwater sculpin in his nest during a dive in Pannerden. After the female had deposited the eggs the male took care of fertilization and he will remain near the eggs to protect them.

Kingfisher tries to eat stickleback, video


This video is about a kingfisher in the Netherlands, who has trouble in eating a three-spined stickleback.

Ronny Bouwens from the Netherlands made the video.

Sea snail venom evolution, new research


This video says about itself:

11 January 2012

You’d think a snail wouldn’t be much threat in the sea, but the cone snail proves deadly to unsuspecting fish.

From the University of Michigan in the USA:

Predatory Snails Evolved Diverse Venoms to Subdue a Wide Range of Prey Species

Released: 17-Mar-2015 8:00 AM EDT

ANN ARBOR—A new study by University of Michigan biologists suggests that some predatory marine cone snails evolved a highly diverse set of venoms that enables them to capture and paralyze a broad range of prey species.

When cone snails sink their harpoon-like teeth into their prey, they inject paralyzing venoms made from a potent mix of more than 100 different neurotoxins known as conotoxins.

The genes that provide the recipes for conotoxin cocktails are among the fastest-evolving genes in the animal kingdom, enabling these snails to constantly refine their venoms to more precisely target the neuromuscular systems of their prey.

U-M researchers showed that the mix of neurotoxins in cone-snail venom varies from place to place and is more diverse at locations where the snails have a broad range of prey species. In addition, they concluded that the observed patterns of local conotoxin variation are likely due to natural selection.

That’s a significant finding because it is often difficult for biologists to determine whether place-to-place variations in an organism’s observable traits—the wide range of beak sizes and shapes in the Galapagos Islands finches studied by Charles Darwin, for example—are the result of evolution by natural selection or some other factor, such as the reproductive isolation of a population of animals or plants.

In addition, the U-M researchers were able to directly target the genes responsible for the observed conotoxin patterns. A paper summarizing the work is scheduled for online publication in the journal Proceedings of the Royal Society B on March 18.

“The differences in venom composition that we observed correspond to differences in prey, and a higher diversity of venom is used to capture more prey species,” said first author Dan Chang, formerly a doctoral student in the U-M Department of Ecology and Evolutionary Biology and now a postdoctoral researcher at the University of California, Santa Cruz.

“Our results suggest that prey diversity affects the evolution of predation genes and imply that these predators develop a more diverse venom repertoire in order to effectively subdue a broader range of prey species,” Chang said.

The study involved a common species of tropical, worm-eating cone snail, Conus ebraeus, collected at locations in Hawaii, Guam and American Samoa. These snails are about an inch long and are commonly known as Hebrew cone snails. Their shells are white with black rectangular markings that form a distinctive checkerboard pattern.

The researchers characterized the patterns of genetic variation in five toxin genes in C. ebraeus snails from the three locations. They also collected fecal samples from the snails to determine the types of worms they ate.

“We demonstrated that venom genes used for predation are highly affected by local variation in prey diversity and geographic heterogeneity in prey compositions,” Chang said. “Not all conotoxin genes are affected in the same way though, which implies that these genes may have distinct functional roles and evolutionary pathways.”

The other U-M authors are Thomas Duda and Amy Olenzek. The study was funded by a National Science Foundation grant to Duda, who is an associate professor in the Department of Ecology and Evolutionary Biology and an associate curator at the U-M Museum of Zoology.

Dan Chang
Thomas Duda

‘Conus geographus, the Life and Death Cone Snail’ by Andreia Salvador: here.