In the warm tropical ocean around the Great Barrier Reef, the lionfish hunts. Venomous fins fan out to trap a school of smaller fish. The little fish look for an escape. But this lionfish is not hunting alone.
As we grow up, we learn to share, take turns and cooperate. Now it seems lionfish use the same skills for a more deadly purpose. New research shows lionfish hunt better when they cooperate with other lionfish, and that they share the meal evenly.
Lionfish are predators and use their long, stripy fins to corner prey. While working on the Great Barrier Reef, Oona Lönnstedt from James Cook University in Queensland noticed something strange. “I did a lot of observations at night and this is when I noticed how they seemed to hunt together in groups, spreading out their large pectoral (side) fins almost like fishermen with their nets”
Curious about the behaviour, Oona went back to the lab and used a maze-like aquarium to observe how lionfish behaved when there was prey around and a second lionfish nearby.
If the first lionfish found prey, it would swim to the second lionfish and do a display. It would put its head down and wriggle its tail fin. Then it slowly waved one side fin, and then the other side fin. The second lionfish almost always responded by waving back and following the first lionfish to hunt. If the second lionfish didn’t follow, the first one would come back and do the display again.
The two lionfish worked together to hunt by using their big side fins to herd the prey fish into a corner. The first lionfish, the one that started the hunt, usually took the first bite. After that they took turns and shared the feast evenly. This behaviour even happened when the two lionfish were different species, for example when a zebra lionfish partnered with an antennata lionfish.
Hunting as a team was very successful. When they were together, each lionfish ate more than they did when they hunted alone. Oona and the team think this complex hunting behaviour might be one reason why invasive species of lionfish are causing problems in the Caribbean. Their teamwork technique is killing too many prey fish, threatening the whole ecosystem.
Lionfish wave their big side fins before going on a group hunt. Image: Wikimedia Commons/Jens Petersen
Quiz questions
What is dendrochronology?
Which baby animal is called a puggle?
Would you be most likely to find feldspar a) in the bark of a tree, b) on a scorpion, or c) in a rock?
What is the largest moon of Saturn?
True or false? Bacteria cells outnumber human cells in the body.
Robogals Science Challenge. Making science and engineering fun!
Entries for the 2014 Robogals Science Challenge are open.
The Science Challenge is an online competition that challenges girls to create and conduct science and engineering projects and share their discoveries in the form of videos and photos.
The competition is open to girls aged between five and 15 years, and is divided into three age groups. Participants have the option of entering as an individual or a team of two, accompanied by a mentor who is over the age of 18 years.
Cut a strip of paper seven centimetres from the long edge.
Fold the paper strip in half and half again, forming a square. Unfold and cut on the creases so you have four squares.
Fold a one centimetre strip along one edge of a paper square.
Turn the paper over and fold one centimetre from the last fold. You are making a zig-zag, accordion-style fold.
Use sticky tape to cover one end of the folded paper, just enough to hold it together.
Spread out the other end of the paper like a fan.
With sticky tape, attach two paper fans to each fork. It should make a T-shape with the points of the fork still sticking out.
Try to stick the fork in grapes! Try with one fork first, then see if having a second fork and working in a team makes it easier.
You will need
Two forks
A4 coloured paper
Ruler
Pencil
Scissors
Sticky tape
Six grapes
Cutting board or large plate
A partner
What to do
Using the ruler and a pencil, draw a line seven centimetres from the long edge of the piece of paper.
Cut along the line so you have a strip of paper.
Take the strip of paper and fold it in half and half again to make a square.
Unfold the strip of paper. The paper will have creases where it was folded. Cut along the creases so you have four squares of coloured paper.
Take one square of paper. Fold a one centimetre strip along one edge, and turn the paper over. Then fold one centimetre from the last fold. You are making a zig-zag, accordion-style fold (like a fan). Each fold should be about one centimetre wide. Keep turning the paper over and folding until you reach the other edge of the paper.
Use sticky tape to cover one end of the folded paper, just enough so that the sticky tape holds the folds together.
Spread out the other end of the folded paper, so it looks like a fan.
Repeat step 5 to 7 for the three other squares of paper.
Put a fork on the cutting board so the fork is upside down with the points pointing away from you. Take a paper fan and tape the sticky-taped end to the fork, about a centimetre from the points of the fork, so the fan points left. Now, tape a second fan to the right. The fans and fork should make a T-shape, but with the points of the fork sticking out above the T.
Repeat step 9 for the second fork.
The forks will be our lionfish, and the paper fans are their fins. The lionfish are going to hunt grapes on the cutting board. The lionfish catches a fish when the fork sticks into a grape.
Put six grapes on the cutting board.
First, try hunting with just one 'lionfish'. Use one fork and try to stick the fork in the grape. You must ‘swim’ towards the 'fish' from the side – you can’t stab downwards.
It’s quite tricky with just one 'lionfish', so see if it’s easier with a friend. Give your partner the other fork, and see if you can work together to stick the forks in the grapes. Remember that you have to ‘swim’ towards the grapes, not stab downwards. Take turns so both 'lionfish' have a chance to catch the 'fish'.
What’s happening?
It’s tricky to spear a grape with just one fork because it takes some force to push the points through the outside of the grape, and the grape keeps rolling away! Having a second fork gives you something to push the grape against.
Lionfish hunt in groups so they can use their long side fins to herd prey into a small area and stop them escaping. One difference between the grapes and real fish is that grapes can only roll across the cutting board, but real fish can swim up and down in the water.
Applications
Most predators hunt alone. Only a few species hunt cooperatively, such as lions, hyenas, chimpanzees, humans, moray eels and some fish. To make cooperative hunting worthwhile, there must be an advantage. Recently, scientists found that lionfish are more successful when they hunt in teams. In a team, each fish eats more than it does when it hunts alone.
Watch it! BrainCraft answers the question 'Why do we feel hungry?'
Quiz answers
Dendrochronology is the study and dating of annual growth rings in trees.
A puggle is a baby echidna.
c) Feldspar is found in rocks. It is a common mineral in the Earth’s crust.
Titan is the largest moon of Saturn.
True. Your body has ten times more bacterial cells than human cells!
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