The Amazing Ocean Sunfish

Georgina Hayes PADI SI #411108 BSc Hons. Zoology MOLA WHAT?

• Sunﬁsh in Bali have almost always been referred to as Mola Mola • Actual species name is “mola ramseyi” or “bumphead sunﬁsh” • In 2017 it was found that this species had actually been already described in 1839 as “mola alexandrini” and this is the mola’s true name.

(zubludiving, 2019) MEET THE MOLA

• Mola mola – or common sunfish is heaviest known bony fish – can weigh up to 1000kg! • Length can reach up to 3.5m • Mola Alexandrini has a temperature range between 10 and 27.5∘ C and depths from the surface to 250 m. Dive depths can extend below 400 m, They basically look like a giant squashed football! (zubludiving, 2019) This unusual fish swims by flapping its long pectoral and dorsal fins; the caudal fin is used as a rudder (for steering) One of the interesting structures that ocean sunfish have is a thick layer of collagen just under the very thin, rough skin. This white tissue is hard and surrounds the body cavity of the fish. No one is sure of the function of this tissues, but it is assumed as protection for the organs

nebshark.org Skeleton of Mola mola

By their “teenage years” they will no longer have a tail ﬁn, no ribs, a fused spine and their beak like mouth will stay permanently open

(Naturhistorisches Museum Wien, 2009) The female Mola can produce more eggs at once than any other known vertebrae – 300 at once!

At birth – Mola larvae are star shaped and the size of a pin head

On a diet of jellyﬁsh they can grow up to 60million times their original weight (G. David Johnson, 2005) WHAT DO THEY EAT?

• Mola have the unique ability to suck in water and spit it out to attack prey • Feed on jellyﬁsh, brittle stars and comb jellies – both deep and shallow water. • Diet is nutritionally poor • Claw like teeth in throat which rips apart food. (Georgina Hayes 2019) SOME LIKE IT COLD…

• Mola anecdotally prefer the colder water – mola season is known for it’s crazy thermoclines • Temperatures in the south can be 18 degrees and even dip lower • To better understand the relationship between mola and temperature the “Bali Ocean Sunﬁsh Research Project” have been using temperature logging devices underwater since 2013 • Currently it is believed they like to live in deep colder water – best time to see mola is when the water temperature drops! (June - October)

• Use upwellings of cold water to approach the surface to be cleaned

(Robert Delfs 2008) SPA DAY FOR THE MOLA

• Mola approaching the surface are there to be cleaned • Up to 50 parasites in and around mola have been found – hence the need for cleaning! • Bannerﬁsh and seagulls aid cleaning process (Tamarind Divers 2019) (MensJournal.com 2019)

(Reinhard Dirscherl 2010)

THREATS TO SURVIVAL

(University of Tasmania 2018) MOLA CITIZEN SCIENCE • Photo submissions from the public can help with identiﬁcation, recognising individuals and species injury rates

SO WHAT MAKES A GOOD PHOTO? • Side on photos – one side is ﬁne, both sides if possible is better • As few obstructions as possible • Images clear enough to see skin patterns • No photo manipulation http://www.thebalisunfish.org/matchmymola/ MOLA CITIZEN SCIENCE

DON’T FORGET THE DATA! • Date of sighting • Time of sighting • Dive site • Depth of Mola – estimation is ﬁne • Coldest temperature on the dive • A name! If the mola is unnamed then you get to name it!

http://www.thebalisunfish.org/matchmymola/ MOLA CODE OF CONDUCT

• Always approach Mola Mola very slowly within its field of view. • If the fish are just entering the cleaning station, do not approach until the cleaning has begun and the fish have been stationary for at least 1 minute. • Maintain a minimum distance of 3m (or 2 body lengths) from the closest sunfish when animal is at a cleaning station. • Maintain a minimum distance of 10m (or 5 body lengths) when an animal is unsettled (not in cleaning) and considering approach to the reef. • DO NOT TOUCH.

(Coral Triangle Centre – MMF) MOLA CODE OF CONDUCT • DO NOT FEED. • Do not swim behind the Mola Mola as this can startle the animal. • Do not swim under the ﬁsh as your bubbles will disturb cleaning behaviour. • Wherever possible, do not block the Mola Mola’s escape route off the reef or pathway onto a cleaning station. • If a Mola Mola approaches you, remain still and do not touch it. If you touch it, you will remove the layer of mucus that protects it against infection.

(Coral Triangle Centre – MMF) MOLA CODE OF CONDUCT

• Do not use ﬂash photography as this often disturbs the ﬁsh. • Do not use personal underwater motorized propulsion vehicles or make unnecessary loud noises. • Be courteous to other divers and restrict your interaction time to 5 minutes when other groups are present. • Only dive with companies which have endorsed and adhere to the Code of Conduct. Follow the directions of your dive guide.

(Coral Triangle Centre – MMF) (The Green Fins) (The Green Fins) WANT TO FIND OUT MORE?

• https://www.zubludiving.com/conservation/the-bali-ocean-sunfish- research-project • http://www.thebalisunfish.org/matchmymola/ • https://en.wikipedia.org/wiki/Mola_alexandrini • https://australianmuseum.net.au/learn/animals/fishes/southern- ocean-sunfish-mola-ramsayi/ • https://www.newscientist.com/article/2155913-record-breaking- two-tonne-fish-is-the-heaviest-of-its-kind/ • https://marinemegafaunafoundation.org/ ANY QUESTIONS? facebook.com/ceningandivers

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