Barmy Barnacles

Morning all,
A beautiful warm sunny afternoon full of wows and fun!
Discarding bags and jackets we set off in two groups to collect some ocean water in our aquaria to place rocks with barnacles attached.
We sat and watched as slowly one by one the barnacles came out to feed, fanning the water in search of plankton and detritus.
The children were all in awe as they watched these tiny limbs.
As we watched we discussed the barnacle anatomy. Looking at the illustration of the barnacle we could see frame by frame how the barnacle opens it’s plates releasing the feathery limbs inside. A barnacle has around 6 pairs of limbs depending on the species. The barnacle is surrounded by six plates with two that slide across the limbs when not feeding.
Checking out the innards the children discovered that a barnacle has a stomach, mouth, anus, one eye (recognizes the difference between light and dark), that a barnacle has no true heart but a sinus with muscles that pump the blood throughout to pick up oxygen, and that barnacles are hermaphrodites.
We discovered that barnacles have no gills. After  much discussion with regards to how the barnacle absorbs oxygen they found out that barnacles absorb oxygen through their limbs, this got a few “cools!” and wishes that they could do this until someone pointed out that if you stepped on poo then you would be in trouble…..
Once we had recovered from the giggle fit reproduction was up next. When asked how the barnacle would reproduce considering they are fixed to a rock and also considering the fact that even though the barnacle is a hermaphrodite it cannot use it’s on eggs and sperm to reproduce the children looked perplexed.Soon though they were coming up few pretty fantastical ideas, including flying barnacles!?!
Barnacles are located in close proximity together. They have been given a penis that is eight times their body length,so can travel to find a willing barnacle.
Barnacles hold fertilized eggs and incubate for 2 months and then release them into the ocean. The plankton has two larval stages, feed and develop for two months before settling on a hard substrate.
The children were pretty impressed when we looked at this more closely using an illustration.
We could see the two larval stages and then the coolest part, how the barnacle attaches itself to a rock.
The larva has cement glands that form at the base of the antennae. These antennae attach to the rock and the barnacle builds the plates around the body. The barnacle spends the rest of it’s life upside down, fanning out it’s legs bringing them down to it’s mouth. Amazing!! Suddenly we had many demonstrations of children fixing their heads to rocks and yelling I’m a barnacle!
Time for a game. We discussed how strong and powerful animals living in tide pools really are. Exposed twice a day and enduring strong water flow. We did a version of red rover but with tides and barnacles. Most survived but a few floated off.
Then the favourite game of the day. Half the group attached feathery felt to their feet and lay on their backs. The other half were the plankton launchers, throwing Velcro covered plankton balls into the air with the barnacles waving their feet in an attempt to catch and feed. Hilarious as you can imagine.
Off we then went to explore with our microscopes, finding crabs with eggs, ocean sow bugs, hermit crabs and checking out barnacle shells and dried bodies on the rocks with our microscopes. Sounds of awe frequently being heard. We did find something that I had never seen before. I was reluctant to tell the children on the day what I thought what we found was but on further investigation I was right. We found BARNACLE EATING NUDIBRANCHS ( noo-dee-brank). Not only 1 but 5 laying EGGS!! I have attached the pic from the day to remind the children.
Once we had spent an hour exploring  we headed back up the beach to play “crowded house”.
Barnacles will compete for space by swamping (many barnacles covering an area) and fast growth.
Mussels and limpets will displace barnacles.
Adult barnacles release compounds into the ocean to attract the plankton to settle near them-swamping.
The more barnacles the likeliness of survival and reproduction.
We set up obstacles in a confined area set out with cones. A barnacle and mussel stood on a rock. A barnacle and mussel plankton stood opposite them on the other side of the obstacles. To the side was a jellyfish and his handler. The jellyfish, mussel and barnacle were blindfolded. The adults and handler had to direct them to the rock for the mussel and barnacle and the handler had to guide the jellyfish to the plankton. The adults and handler using directions to guide them. If the plankton touched an obstacle they had to return to the beginning, if touched by the jellyfish then they were out of the game.
Sometimes the barnacles would crowd out the mussels on the rock and sometimes the mussels would win, one thing for sure was the fact giggles and laughter could be heard along the beach and the occasional frantic direction! There was chaos……..
Have a great week,










Apr 27, 2012 | Category: Uncategorized | Comments: none


Leave a Reply