July and August are peak months for jellyfish sightings in Scotland, and scuba diver and underwater photographer Ross McLaren says his first encounter left him with "sheer terror". He was stung across the upper lip during a dive in the Clyde, but says the experience did not put him off diving.
Many people fear jellyfish because of painful stings and their unpredictable movement in the water. But McLaren, who lives near the coast in North Ayrshire and has completed almost 600 dives since 2016, says there is much more to the brainless, heartless and boneless invertebrates than people might think.
"sheer terror"
"I was diving in the Clyde and one of the instructors had to pull me out of the way of the tentacles as it was wafting above me," he said.
He said jellyfish have a bad reputation, but he considers them among the most striking creatures underwater.
"Jellyfish have such a bad reputation but they are one of the most mesmerising and beautiful creatures underwater," he said, having completed almost 600 dives.
As Scotland reaches peak jellyfish season, the question is whether they should be seen as something to admire or something to avoid.
When do you see the most jellyfish in Scotland?
July and August are peak months for jellyfish sightings in Scotland. Anna Bunney of the Marine Conservation Society, which runs a nationwide survey of jellyfish, said the number and distribution of jellyfish are affected by several factors.
"The number and distribution of jellyfish are impacted by many different factors," said Anna Bunney of the Marine Conservation Society, which runs a nationwide survey of jellyfish.
"This includes sea temperatures, the availability of plankton for feeding, which peaks during the summer months when it is warmer, and ocean currents."
Sea temperatures tend to lag behind air temperatures, Bunney said. The maximum air temperatures in Scotland usually occur in July and August, whereas sea temperatures are warmest in August and September.
When the sea begins to warm, jellyfish return in greater numbers.
Sea temperatures, plankton availability and ocean currents all affect sightings in Scotland.
Bunney described jellyfish as weak swimmers, or "passive drifters", that depend on currents to move them along.
Calmer ocean conditions around the UK in the summer months help push jellyfish gently towards the shore, which means there are often more sightings.
Warmer conditions also speed up breeding, allowing adult jellyfish to reproduce in large numbers and form so-called blooms.
These blooms can resemble a thick soup or pulsing cloud in the water and have been known to block boat engines.
In 2011, Torness nuclear power station in East Lothian was shut down as a precaution after huge numbers of jellyfish were found in seawater entering the plant.
McLaren said jellyfish season normally runs from April to October, although they can be seen in Scottish waters all year round.
"You see them in the winter months but they are far more prevalent and common during the summer," he said.
What happens if a jellyfish stings you?
Jellyfish stings in Scotland are not usually life-threatening, but they can be very painful. Depending on the species, the stingers may not be sharp enough or long enough to pierce the skin.
Bunney said most jellyfish have stinging cells, but the severity and detectability of the sting vary widely between species.
Swimmers should be aware of the Lion's Mane jellyfish, which is brownish orange and common around Scotland's coastline in the warmer summer months.
Its long tentacles can deliver a painful but not lethal sting.
The tentacles can break off and float in the sea or attach to chains on a boat, for example, but the stinging cells remain alive even when they are no longer attached to the main body.
"The Lion's Mane jellyfish have long tentacles which can give painful stings"
Bunney, who said she has been stung a lot by jellyfish, compared a mild sting with that of a nettle.
"There was one point when every time over a period of two years I was stung by a jellyfish when I was out in the sea," she said.
"But thankfully, it hasn't impacted how I feel about the ocean.
"In fact, what I often think is the most frustrating is when you are stung but you cannot see what you have been stung by."
The Barrel jellyfish has eight arms and is not normally harmful to humans.
McLaren said he has never been put off scuba diving by the possibility of a jellyfish sting, but he understands why swimmers may feel nervous.
"When you're diving, as long as the visibility is good, you can negotiate your way around a jellyfish relatively easily, if you know what way the current is flowing and you pay attention," he said.
"Swimming, on the other hand, I totally get it - if I was taking my kids down to the beach and there were a lot of jellyfish I would probably stop them from getting in the water.
"When you're swimming you tend to have your head out of the water more so you can't always see what is underneath or know where the tentacles are going."
Bunney and McLaren both said it is important not to touch a jellyfish washed up on a beach, because it can still sting even when it is presumed dead.
Jellyfish tentacles can still sting when they are not attached to the main body.
Bunney said people should follow NHS guidance after a jellyfish sting.
It advises using tweezers or the edge of a bank card to remove the tentacles as soon as possible, because they can continue to sting while attached to the body.
A heat pack or immersion in hot water can reduce pain and swelling, and painkillers such as paracetamol can also help.
If symptoms become more severe, or if a sensitive part of the body has been stung, medical help should be sought.
Why do jellyfish sting?
Jellyfish sting as an automatic reflex, not as a deliberate attack.
Unlike bees or wasps, which sting as a defence mechanism, a jellyfish sting is an automatic response rather than a conscious action.
"A common misconception is jellyfish go after people but contact with a jellyfish is actually merely incidental and humans are not on their menu," Bunney said.
"They are not actively stinging, it is just when anything touches their tentacles as they are moving through the water, regardless of what it is."
Small fish often live among jellyfish tentacles for protection.
Jellyfish tentacles are lined with thousands of venom-filled stinging cells. When touched, those cells fire toxic harpoon-like tubes designed to paralyse prey such as plankton and small fish.
Should jellyfish stop you from swimming in the sea?
"Do not be afraid but be cautious" is Bunney's advice, and she generally recommends swimming calmly away from jellyfish.
"Do not be afraid but be cautious" is the advice from Bunney, who generally recommends swimming calmly away from jellyfish.
Most of the species found in Scotland have very mild stings that only cause minor irritation, and some are completely harmless, she said.
"Most of the species found in Scotland have very mild stings, which only cause minor irritation, and some are completely harmless," she said.
Bunney said it is important for people to learn about different species of jellyfish and report sightings to the Marine Conservation Society.
"People think jellyfish are ugly," she said. "But they are really beautiful creatures that come in all different colours and sizes."
McLaren agreed, saying he always tries to photograph jellyfish when he sees them.
"People hate jellyfish but I always do my best to take a photo of one when I see it because they are impressive to see in the water," he said.
"It's almost like stars in the night sky when you are on the sea floor and looking up at the jellyfish above you.
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