The Leafy Sea Dragon – Did You Know?

In my Did You Know series, learn some fun facts about an animal in 5 minutes. I’ll tell you stuff you didn’t already know (hopefully). Let me know if I surprised you!

Today I’ll tantalise your curiosity taste buds with a master of masquerade: the leafy sea dragon.

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The leafy seadragon or Glauert’s seadragon, Phycodurus eques. Photo credit: James Rosindell

Did You Know?

  • It is a species of fish named after the dragons described in Chinese mythology and folklore (and more recently in George R. R Martin’s Game of Thrones)
  • It is the only member of the Phycodurus genus in the Syngnathidae family of fishes.
  • Its resemblance to a piece of drifting seaweed may help to protect it from predators. Its seaweed-like appearance not only allows it to match the background of seaweed and kelp it lives amongst (making it very hard for predators to spot), but it may also serve as a type of camouflage called ‘masquerade’. This is when an animal tricks its predator into thinking it’s an inedible object that isn’t dinner, similarly to that seen in leaf and stick insects. If you’re interested, you can read more about masquerade here and here.
  • Another aspect of this ‘floating seaweed’ trick seems to be the sea dragon’s sedate movement through the water. It moves at a slow rate of about 150m per hour propelled by fins along the side of its head but often stays in the same place for long periods of time.

 

 

  • Unusually in the animal kingdom, the male is the sole responsible parent. The female deposits 150-250 bright pink eggs onto the male’s tail, and then leaves him to it. He carries them in a honeycomb-like structure called the brood patch for 8 weeks where they are supplied with oxygen until the young emerge (like its relatives: seahorses, pipefish and other sea dragons). Only about 5% of the eggs survive and the young are completely independent at birth.
  • It feeds exclusively on small crustaceans like mysid shrimp.
  • Their natural habitat is calm, cold water (10-12 degrees Celsius) in the southern coasts of Australia, where they are known locally as ‘leafies’.
  • It is classified as Near Threatened by the IUCN Red List 2006, and may even be reclassified as Endangered, mainly due to habitat loss and pollution through human activity.
  • It has been protected by the Australian government since 1982 and is the marine emblem for the state of South Australia.

Thanks for reading and look out for other posts in my Did You Know? series!

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Scientific American video about my research on lizard camouflage

Scientific American have produced a great video about my PhD research on lizard camouflage in Greece. I found that lizards are able to pick certain rock backgrounds to sit on that make them most camouflaged to a predatory bird’s eye. Intriguingly, this means that somehow they know the colour of their own backs and how well it will match a given rock – a puzzle I haven’t quite worked out yet. You can watch the video here.

 

Octopuses – Did You Know?

In my new Did You Know blog series, learn 10 fun facts about one animal in 5 minutes. In the series, I’ll tell you stuff you didn’t already know (hopefully). Let me know how many surprised you! Let’s start off with one soft-bodied cephalopod: the octopus. 

Did You Know that octopuses…

1. …Have three hearts. Yup! One pumps blood through the body (systemic) and the other two pump blood through each of the two gills (branchial).

2. …Have a relatively short life expectancy. Some smaller species live for only 6 months.

3. …Can die from reproduction. Females can die of starvation after their eggs hatch (they don’t eat while they take care of unhatched eggs), and males can die immediately or a few months after mating. Sexual unhealing.

4. …Can kill a person. The blue-ringed octopus bite is so toxic it can kill you within minutes. Not a great choice for a pet.

5. …Usually have no internal skeleton. The only hard part of their body is the beak (except in octopuses of the Cirrina order, which have an internal shell).

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The greater blue-ringed octopus (Hapalochlaena lunulata). Wikipedia Commons. Blue-ringed octopuses are known to be one of the world’s most venomous marine animals.

6. …Have a beak that helps them squeeze through very narrow gaps when escaping from predators like moray eels and predatory fish.

7. …Have eight arms with suction cups that are highly touch-sensitive. The suction cups help them sense many aspects of their environment, such as recognising other octopusessurface curvature and shape, and taste.

8. …May eject viscous ink when they feel threatened. Inking in cephalopods acts as a defence by distracting and deterring predators, provides a smokescreen to hide behind, and causes sensory confusion in predators, such as by mimicking the smell of food.

9. …Are highly intelligent among invertebrates. They are quick to solve problems and some have been known to use tools, reflecting their superior cognitive abilities.

10. …Can change colour in a matter of seconds or minutes to match or mimic their environment for camouflage against predators, to flash a warning signal, and to signal to other octopuses.

Feel free to make suggestions about other animals you want to see featured in the series!