How guppies dodge predators


This 2013 video is called Guppy (Poecilia reticulata) evades strike from pike cichlid (Chrenicichla alta).

From the University of Exeter in England:

‘Matador’ guppies trick predators

June 11, 2020

Trinidadian guppies behave like matadors, focusing a predator’s point of attack before dodging away at the last moment, new research shows.

The tiny fish (10-40mm) draw attention by turning their irises black, which makes their eyes very conspicuous.

This encourages pike cichlids — a large fish that is the guppies’ main predator — to charge at their head rather than their body.

The international study, led by the University of Exeter, found guppies then use their lightning reflexes to whip their head out of the way, causing the predators to miss, before swimming away.

Many fish, including guppies, often approach their predators to find out if they are hungry and thus a current threat.

“We noticed that guppies would approach a cichlid at an angle, quickly darkening their eyes to jet-black, and then waiting to see if it would attack,” said lead author Dr Robert Heathcote, who undertook the experimental work at Exeter and is now at the University of Bristol.

“Cichlids are ambush predators, lying in wait like a coiled spring before launching themselves at their prey.

“The guppies actually use their eyes to get the predator’s attention, causing them to lunge at a guppy’s head rather than its body.

“Whilst it seems completely counterintuitive to make a predator attack your head, this strategy works incredibly well because guppies wait until the predator commits to its attack before pivoting out of the way.

“The speed of the whole interaction is extraordinary — at around three-hundredths of a second — so was only observable using a high-speed camera.”

Many animals are known to use “conspicuous colouration” for purposes such as communication, attracting mates, startling predators and advertising toxicity.

This paper demonstrates a previously unknown divertive strategy — but the researchers think it may be used by other species too.

“We don’t know for sure, but it seems highly likely that other animals also use a ‘matador’ strategy like the one we have identified in guppies,” said Professor Darren Croft, of the University of Exeter.

“Eyes are one of the most easily recognised structures in the natural world and many species go to great lengths to conceal and camouflage their eyes to avoid unwanted attention from predators.

“Some species, however, have noticeable or prominent eyes and, for the most part, it has remained a mystery as to why this would be.

“Our latest research gives new insight into why ‘conspicuous’ and colourful eyes have evolved.”

The study was conducted in several stages:

  • Guppies were observed approaching pike cichlids, often turning their irises black.
  • The attack strategy of cichlids was tested by placing them in tanks with realistic robotic guppies. When robotic guppies had black eyes, cichlids tended to strike towards the head rather than towards the centre of the body.
  • By placing guppies and cichlids in a tank (with a transparent screen to prevent the guppies being eaten) and filming with high-speed cameras, researchers observed the success rates of cichlid attacks. Guppies that turned their eyes black were 38% more successful at escaping than guppies with normal eye colouration.
  • Findings were then confirmed using footage of a previous study in which cichlids were filmed hunting real guppies.

“This project presented a wonderful range of technological challenges, including the creation of robotic guppies matched to the colour vision of pike cichlids, and high-speed computer tracking of guppies as they escaped,” said Dr Jolyon Troscianko, of the University of Exeter.

“These advances allowed us to work out whether an attack would have been successful without needing to run life-and-death experiments with fish.”

One surprising finding was that larger guppies were better than smaller ones at escaping using this method.

“As animals become larger, they generally become less agile. If larger prey don’t have weapons or other ways of defending themselves, this can result in them being easier for predators to catch,” said Dr Heathcote.

“By turning their eyes black, larger guppies actually reverse this phenomenon.

“Bigger guppies with black eyes are better at diverting and escaping predator attacks.

“Since bigger animals produce more or larger offspring, it would be really exciting to find out if the animals that use these kinds of strategies have evolved to become larger.”

Professor Indar Ramnarine, of the University of the West Indies, St Augustine Campus, said: “We first discovered this particular behaviour in guppies several years ago and wondered what was the significance of this. Now we know.”

Previous research has shown that guppies also turn their eyes black to display aggression towards each other.

Dr Safi K. Darden, of the University of Exeter, said: “We knew that changing iris colour was somehow involved in interactions with other guppies, but when we saw that guppies performing predator inspections were also changing the colour of their irises, we figured that something really interesting must be going on.

“It is thrilling to have had such a skilled team with diverse expertise come together to be able to investigate this behaviour in such detail.”

Female Trinidad guppies save males from starvation


This 3 September 2018 video says about itself:

This video gives an impression of the fieldwork we conduct to study guppy behavior in the rainforest of Trinidad. It also summarizes the main conclusions of our scientific paper in Nature Ecology and Evolution, which examines how being social helps guppies find food.

Reference to Paper: Snijders L, Kurvers RHJM, Krause S, Ramnarine IW, Krause J (2018). Individual- and population-level drivers of consistent foraging success across environments. Nature Ecology and Evolution.

From Forschungsverbund Berlin in Germany:

Male Trinidad guppies find food thanks to females

September 13, 2019

For male Trinidad Guppies applies: if you are hungry, seek female company. A recent study led by scientists of the the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) and the Leibniz Institute for Zoo and Wildlife Research (IZW) together with other research institutions provides evidence that male guppy fish in the presence of females more often ended up at novel food patches. In contrast, female food discovery was independent of male presence.

Trinidad guppies (Poecilia reticulata) live in small watercourses in the rainforests of Trinidad. They have a preference for sporadic high-quality food resources, like fruits and insects, falling into the water- so it is usually uncertain when and where they encounter food. In this study, behavioural ecologist Lysanne Snijders and her team set up a field experiment and manipulated guppy sex compositions (all male, all female or mixed) in the wild using individually colour-marked guppies. They conducted social observations, followed by foraging trials.

Males reached more food patches when there were females around. Yet, females reached a similar number of patches either with or without males present. Males also spent less time social in absence of females, but the absence of males had no effects for females. The researchers analysed if this time spent socially was linked to patch discovery success. Indeed, in agreement with a previous study, more social guppies ended up at more food patches.

“Life in the group can be advantageous. You have to share the food with your peers, but it is also easier to find it if you use the information of others,” explains Lysanne Snjiders. Guppies, for example, react to the typical behaviour of successful food finders, which is: swim faster, grab food, stay there and eat.

The researchers can only guess why males behave differently in the absence of females than in sexually mixed groups. “In this case, males among themselves are more likely to be in a state of competition than cooperation and therefore spend less time together and miss out on important information,” says Lysanne Snijders.

The head of the study, IGB-researcher Prof. Jens Krause, is investigating the dynamics of swarm behaviour and collective intelligence in animals. He explains the importance of this field of research: “If we are able to understand the interactions of animals within a group, we can derive from this knowledge information about the spread of diseases, reproduction and predator-prey relationships. The structure of social networks may also be a decisive factor concerning the stability of a population. Such knowledge may help wildlife managers and conservationists, for example, to optimise disease management, breeding programmes or reintroduction activities.”

Guppies, a perennial pet store favorite, have helped a UC Riverside scientist unlock a key question about evolution: Do animals evolve in response to the risk of being eaten, or to the environment that they create in the absence of predators? Turns out, it’s the latter: here.

Leadership during cooperation runs in the family for tiny fish called Trinidadian guppies, new research shows. University of Exeter researchers studied leadership in guppies by selectively breeding for fish that differed in how likely they were to lead a scouting party to examine a predator: here.

When it comes to finding a mate, male guppies rely on their brothers to ward off the competition. In a new study published by a Florida State University team, researchers found that male Trinidadian guppies observe a form of nepotism when it comes to pursuing the opposite sex. These tiny tropical fish often help their brothers in the mating process by darting in front of other males to block access to a female: here.

Trinidadian guppies have individual personalities, new research


This 2014 video says about itself:

Sustainable Innovation Initiatives (SII) creates bridges between research, business, industry, tourism and educators to make ecological sustainability a priority for societies in tropical forest ecosystems. Our upcoming documentary series helps us accomplish this goal by reaching many people through video.

“Home of the Guppy” is our first episode. It highlights unique features of research in the Northern Range of Trinidad and grassroots efforts in habitats critical to this watershed and communities that use it.

Home of the Guppy Summary: Streams in Trinidad’s Northern Mountain range have been epicenters for breakthroughs in evolutionary theory over the last five decades.

A unique combination of isolation, species-diversity and system-replication has created a “natural laboratory” like no other in the world. These unique conditions have allowed scientists to examine every guppy in multiple wild populations for as many as 15 generations. Guppy studies in Trinidad have produced one of the most detailed multi-generation data collections ever compiled in a wild vertebrate. Results from these studies are reshaping longstanding views of evolutionary theory.

From the University of Exeter in England:

Fish have surprisingly complex personalities

Tiny fish called Trinidadian guppies have individual ‘personalities,’ new research shows

September 25, 2017

Scientists from the University of Exeter studied how guppies behaved in various situations, and found complex differences between individuals.

The researchers tested whether differences could be measured on a “simple spectrum” of how risk-averse or risk-prone guppies were. But they found variations between individuals were too complicated to be described in this way.

“The idea of a simple spectrum is often put forward to explain the behaviour of individuals in species such as the Trinidadian guppy,” said Dr Tom Houslay, of the Centre for Ecology and Conservation (CEC) on the University of Exeter’s Penryn Campus in Cornwall.

“But our research shows that the reality is much more complex. “For example, when placed into an unfamiliar environment, we found guppies have various strategies for coping with this stressful situation — many attempt to hide, others try to escape, some explore cautiously, and so on.

“The differences between them were consistent over time and in different situations. So, while the behaviour of all the guppies changed depending on the situation — for example, all becoming more cautious in more stressful situations — the relative differences between individuals remained intact.”

The study, published in the journal Functional Ecology, examined the “coping styles” of guppies in conditions designed to cause varying levels of stress.

Mild stress was caused by transferring fish individually to an unfamiliar tank, and higher levels of stress were caused by adding models of predatory birds or fish.

The presence of predators had an effect on “average” behaviour — making all of the guppies more cautious overall — but individuals still retained their distinct personalities.

Professor Alastair Wilson, also from the CEC at the University of Exeter, added: “We are interested in why these various personalities exist, and the next phase of our research will look at the genetics underlying personality and associated traits.

“We want to know how personality relates to other facets of life, and to what extent this is driven by genetic — rather than environmental — influences.

“The goal is really gaining insight into evolutionary processes, how different behavioural strategies might persist as species evolve.”

The paper is entitled: “Testing the stability of behavioural coping style across stress contexts in the Trinidadian guppy.”

When evolving in environments where a lack of predators makes food scarcity the main survival challenge, guppy mothers gestate their young longer so that they are born more ready to compete for their meals: here.

Female guppies with smaller brains can distinguish attractive males, but they don’t recognize them as being more appealing or choose to mate with them, according to a new study. The study adds weight to the link between mate preference and cognitive ability: here.

Female guppies’ brains and choice of mates


This video says about itself:

4 October 2014

Sustainable Innovation Initiatives (SII) creates bridges between research, business, industry, tourism and educators to make ecological sustainability a priority for societies in tropical forest ecosystems. Our upcoming documentary series helps us accomplish this goal by reaching many people through video. “Home of the Guppy” is our first episode. It highlights unique features of research in the Northern Range of Trinidad and grassroots efforts in habitats critical to this watershed and communities that use it.

Home of the Guppy Summary:

Streams in Trinidad’s Northern Mountain range have been epicenters for breakthroughs in evolutionary theory over the last five decades. A unique combination of isolation, species-diversity and system-replication has created a “natural laboratory” like no other in the world. These unique conditions have allowed scientists to examine every guppy in multiple wild populations for as many as 15 generations. Guppy studies in Trinidad have produced one of the most detailed multi-generation data collections ever compiled in a wild vertebrate. Results from these studies are reshaping longstanding views of evolutionary theory.

What it means for the world

Features of Trinidad’s stream ecology enable mergers between field and laboratory studies that connect traits such as lifespan, age of maturity and mate-selection, to functions such as cognition and cooperation. Work with Trinidad’s guppies demonstrates the first time that so many traits have been connected with such detail in a wild organism under multiple conditions. Data from Trinidad’s streams has powerful implications for models of evolution and conservation, as well as population management of rare, common and commercially valuable species. Work in Trinidad also vastly updates our understanding of how ecology and evolution are intertwined, and has led to upheavals regarding the time-scales on which the two processes were previously thought to function.

Why are we making this film?

Trinidad’s Northern Range exemplifies how diversity contained in less than 400 square miles of habitat is influencing the world of biology. However it is also valued for land-use, extraction and recreation, as increasing numbers of people utilize the range.

Studying ecology of wild guppies has led to insights affecting applications for biology education, behavioral models, health care and the design of cooperative networks. These applications are assigned high value in the global marketplace.

However, Trinidadians have limited access to globally valued information generated by the biodiversity of their land. This documentary connects local communities and global networks for informed management and value-assignment.

This documentary also raises awareness of how guppy studies are affecting standards of modern biology education. We are working with scientists to make this knowledge accessible at multiple levels of outreach. Our documentary contributes to the type of information access needed for the types of societal functionality that enable sustainable management.

From Science News:

Female guppies with bigger brains pick more attractive guys

But the additional mental power has downsides, too

By Susan Milius

3:54pm, March 22, 2017

When choosing more attractive guys, girl guppies with larger brains have an advantage over their smaller-brained counterparts. But there’s a cost to such brainpower, and that might help explain one of the persistent mysteries of sex appeal, researchers report March 22 in Science Advances.

One sex often shows a strong preference for some trait in the other, whether it’s a longer fish fin or a more elaborate song and dance. Yet after millions of years, there’s still variety in many animals’ color, size, shape or song, says study coauthor Alberto Corral-López, an evolutionary biologist at Stockholm University. Somehow generations of mate choice have failed to make the opposite sex entirely fabulous.

Mate choice could require a certain amount of brainpower, with animals weighing the appeal of suitors and choosing among them. Previous research suggests a smaller brain dims guppies’ mental abilities, and the researchers wondered how brain size might affect the fish’s choice of mate.

To test the idea, researchers used female guppies bred for either a larger or smaller brain. Guppy brains are tiny to begin with, but after five generations of breeding the brain sizes in the study differed by about 13 percent, within the range of what biologists find in the wild.

Each female was offered a choice between a colorful male with orange spots and a bigger tail versus a drab male of about the same weight but without much glory behind. The male fish were installed in compartments at either end of a tank, and females swam back and forth, forced to remember and mentally compare one suitor with his rival.

Females with larger brains showed a preference overall for the more colorful male. Smaller-brained females showed no preference. (The difference did not come from differences in color vision, Corral-López says. The researchers checked the eye genes of the fish and also tested their ability to distinguish colors.)

Interest in flashy-looking males may not be just a fashion choice for females. Orange colors come from pigments in food, suggesting that brighter males may be better fed and healthier, which could lead to healthier offspring. And more colorful males are typically better at finding food. Corral-López also tested females that had not been specially bred for brain size, and these fish preferred the colorful males, too.

But bigger-brained females did not beat their small-brained compatriots in all tests. The smaller-brained guppies tended to grow faster when they were young and to have better immune systems and more offspring.

Thus, circumstances might tip the balance toward or against braininess, the researchers say. Having more babies might be more useful than a discriminating brain, for instance, when food is plentiful and most males manage a decent orange. Such changes in fortune might help explain how variety in appearance persists despite strong mating preferences, Corral-López and colleagues argue. Sometimes flashier males win females, but sometimes drab is just fine.

“Exciting work,” says Molly Cummings of the University of Texas at Austin, who studies fish brains and sexual selection. Checking the fish’s vision was especially important, she says. The results show that females were not “simple slaves to their sensory system.”

The new paper, of course, tracked lab animals, and there’s little data on what differences in brain size mean for mate choice in the wild, says evolutionary biologist Kimberly Hughes of  Florida State University in Tallahassee. The new guppy study suggests it’s certainly worth looking at what girl guppies do naturally, she says.

Further Reading

L. Hamers. Brain’s blood appetite grew faster than its size. Science News Online, August 30, 2016.

C. Samoray. Forgetful male voles more likely to wander from mate. Science News Online, December 14, 2015.

Dutch seventeenth century shipwreck discovery in Caribbean


Map of the Battle of Scarborough Harbour, 1677

From the University of Connecticut in the USA:

UConn Archaeologist Discovers 17th-century Shipwreck

October 21, 2014

By: Sheila Foran

The Dutch ship Huis de Kreuningen went to her watery grave on March 3, 1677. But until a team led by University of Connecticut professor and maritime archaeologist Kroum Batchvarov found her this past summer in the waters of the southern Caribbean, no one knew precisely where that grave was.

Batchvarov, assistant professor of maritime archaeology in UConn’s Department of Anthropology, is an internationally known researcher specializing in 17th-century ship building and maritime archaeology. He is leading a multi-phased investigation to find and study the remains of 16 vessels that were sunk in a fierce battle that took place in what is now known as Scarborough Harbour in the Republic of Trinidad & Tobago.

The battle was fought between the invading French and the Dutch, who controlled the island of Tobago at that time. Although often overlooked by students of maritime history, the confrontation was significant, both in terms of the number of lives lost and the damage done to both fleets.

Earlier this year, Batchvarov and his team were conducting a remote sensing survey in the Harbour when they picked up some promising signals. An exploratory dive struck pay dirt.

“To find what we believe to be the Huis de Kreuningen – almost by accident, as she was outside the boundaries where we expected to find her – undiscovered and untouched for over 300 years was an exciting moment,” Batchvarov says.

His research team went on to survey and map the wreck over the summer.

The find is a significant source of information for the maritime history of the period. “Although we have some written records of the battle itself, we possess no detailed plans of 17th-century warships,” Batchvarov says, “so our only sources of information about the ships of the day are the wrecks themselves. It isn’t overstatement to say that what has been discovered is a treasure trove for archaeological researchers.”

What is known about the battle is that all told, 2,000 people, including 250 Dutch women and children and 300 African slaves, were killed. In addition to the Huis de Kreuningen, which was the largest ship in the Dutch fleet, the flagship of French Vice Admiral Comte D’Estrée – the Glorieux – was also sunk and all but 80 of the 450 men aboard were lost. In the end, the Dutch lost more vessels, but they succeeded in repelling the French landing party and retained possession of the island.

Batchvarov says although his team didn’t find much of the hull structure intact, they have found a wealth of other material, including nine canons; Delft and Bellarmine pottery jars that date to the third quarter of the 17th century; lead shot that was never fired; dozens of Dutch smoking pipes; and bricks that perfectly match the specifications of bricks made in the Dutch city of Leiden in 1647.

The Huis de Kreuningen, though the largest in the Dutch fleet at 39.6 meters in length and 9.62 meters in breadth, was only about three quarters of the size of her French foe, the much newer and better armed Glorieux. With only 56 guns to her opponent’s 72, and with a crew of 129 instead of her full complement of 290 sailors aboard, existing records of the battle report that she put up a valiant fight until her captain either cut her anchor cables so she would run aground, or set her afire – accounts vary – in order to avoid capture.

Another benefit of the project is the opportunity it provides for students to participate in Batchvarov’s ongoing research. Students enrolled in maritime studies at UConn’s Avery Point campus, the only undergraduate program in the country with a maritime archaeology minor, have a singular opportunity.

On this summer’s trip to Tobago, Mark Wegiel ’15 (CLAS), a former Navy diver, took part in the exploration of the Huis de Kreuningen. With plans for doing graduate work in anthropology with a concentration in maritime archaeology, Wegiel says the dive in Scarborough Harbor gave him a new perspective.

“I had plenty of experience as a diver during my years in the Navy,” he says, “but having the chance to take part in surveying and mapping the wreck and being introduced first hand to the techniques of archaeological exploration was something new and exciting. As an undergraduate, I couldn’t have gotten this experience anywhere else.”

Permission to excavate the shipwrecks in and around Scarborough Harbour has been granted by the Tobago House of Assembly to the Rockley Bay Research Project, which is supported by the University of Connecticut and the Institute of Nautical Archaeology of the United States.

Artifacts and other items found in the shipwrecks are the property of Tobago and will eventually be displayed on the island. Excavation is expected to take three to five years.

In addition to his work in Tobago, Batchvarov is one of the world’s leading experts on the Swedish warship, Vasa, which sank in Stockholm Harbor in 1628. He has worked on Ottoman, Greek, and Phoenician ships, and has recently been invited to participate in an international collaboration that will study ships of state from 1300 to 1800. Batchvarov will concentrate on 17th-century shipbuilding technology development. The only person to have successfully excavated a Black Sea shipwreck, he is also involved in an international collaborative study of the Black Sea littoral zone – or shoreline to the high-water mark – that will concentrate on human adaptation to sea changes from the Upper Paleolithic era to the 19th century. The University of Connecticut is the only non-European institution invited to participate in these important endeavors.

Trinidad and Tobago hummingbirds


This is a video of a white-chested emerald hummingbird.

From 10,000 Birds blog; with photos there:

Hummingbirds of Trinidad

By Mike • August 25, 2012

The Republic of Trinidad and Tobago may share equal billing in the dichotomous nation’s name, but Trinidad boasts the lion’s share of the land mass, population, and hummingbirds. My focus during my June 2012 visit was obviously on the hummingbirds.

Visitors to Trinidad can scarcely help encountering stunning hummers just about everywhere. Between them, Trinidad and Tobago boast 17 species, of which several of which are extremely rare or accidental and one — the endangered White-tailed Sabrewing — can only be found in Tobago and. Most of the usual Trinidadian hummers frequent the feeders at the Asa Wright Nature Centre. The legendary veranda is the perfect place to spy Blue-chinned Sapphire, White-chested Emerald, and three different hermits (Rufous-breasted, Green, and Little) while enjoying good, strong coffee or even stronger beverages.

Are you curious to know the size of the hummingbird chicks? Check out this photo.

Antigua leatherback turtle babies hatched safely


This video from Costa Rica is called Leatherbacks hatch at Gandoca, Limón.

From Caribarena Antigua:

Sandals Protects Leatherback Sea Turtle Hatchlings

Saturday, 23 June 2012 02:30

By caribarena news

Antigua St John’s – Dickenson Bay, June 22- More than forty guests from Sandals Grande Antigua Resort & Spa were treated to something truly special when they witnessed the emergence of leatherback sea turtle hatchlings at Dickenson Bay Beach yesterday.

It had been more than 60 days since the imposing leatherback sea turtle affectionately known as ‘Lady Sandy’ made her way to Dickenson Bay shores to hatch approximately 100 eggs. In the wee hours of the morning on Thursday, June 21, approximately 20 hatchlings came out to the delight of onlookers.

This was followed by a nest excavation in which guests and staff members had the opportunity to guide the hatchlings.

“It was an incredible once in a lifetime experience and I know that guests were thrilled to be a part of it,” said an ecstatic Shernell Connor, who is the Director of Guest Services at Sandals Grande Antigua.

Thanks to the assistance of the Environmental Awareness Group’s Antigua Sea Turtle Conservation Project, another 27 healthy hatchlings emerged from the sand and made their way successfully to the sea.

Coordinator of the EAG’s Antigua Sea Turtle Conservation Project Mykal Clovis Fuller explained the purpose of the nest excavation.

“We want to determine how successful the nesting was so that we can extract data pertaining to the fertilized and non-fertilized eggs and in this case, approximately 50% of the eggs were viable, which is the norm for this critically endangered species,” commented Clovis Fuller.

This is the ending of the nesting season for leatherback sea turtles and there are a select number of beaches that they choose to nest on in Antigua and Barbuda. In fact, four years ago, a leatherback sea turtle came to Dickenson Bay so it is highly likely that it was ‘Lady Sandy’ since these turtles are very loyal creatures.

Leatherbacks are the largest of all the turtle species and the females normally nest every two to three years. Anyone who sees a leatherback sea turtle come to shore is encouraged to call 720-6955.

Thousands of leatherback turtle eggs and hatchlings have been crushed by heavy machinery along a Trinidad beach widely regarded as the world’s densest nesting area for the biggest of all living sea turtles, conservationists said on Monday: here. See also here.