Category Archives: Crustaceans

Let’s Sea About Sea Monkey’s


My brother and sister-in-law have recently tried, not very successfully, to raise a little batch of Sea Monkey’s.  Quite disappointed in the short-lived pets, I was asked how long they typically live for… so I decided to do a bit of research looking into this little species.

For many people, their first pet as a child was a little packet of Sea Monkey’s; lovingly hatched from the eggs received in the packet, after following all the instructions to prepare the little tank for their home… what most people don’t know is, what Sea Monkey’s actually are. Whilst doing some research into this post, I have also come to realise that a lot of people (I’m unsure why…) did not even know that Sea Monkey’s were living creatures!

What Are They?

Sea Monkey’s are an invertebrate species, meaning they do not have a backbone. They are arthropods, meaning they have jointed legs. They are a crustacean; related to crabs, shrimp, water fleas, lobsters; with an exoskeleton, an outer shell. When growing, they shed their exoskeleton and regrow a new one to fit their larger size. Until the new exoskeleton hardens, they are more vulnerable.

They are also known as, Brine Shrimp. If you have followed any previous posts you may have come across this little titbit of information before, in Something Fishy! (1) – as they are a form of live and frozen fish food.

Females vs. Males

Size wise – females are smaller than males; females growing between 8-12 mm in length, and males growing between 10-15 mm in length.

Females have a “lump” at the base of their tail (which is where the eggs are stored), the males do not. Females have small antennae, whilst the males have large, distinct antennae (see image, below).

Female (left), Male (right) - Brine Shrimp
Female (left), Male (right) – Brine Shrimp

Lifespan

My sister-in-law told me that the packet informed her, that Sea Monkey’s can live up to 6 months! That surprised me a bit, as from what I have witnessed and been taught through my studies, is that they typically live 3-5 weeks in the right conditions. The longest I have discovered for the claimed lifespan of the Brine Shrimp is 12 weeks; the average being about 6 weeks.

They last about a week in the fridge, in a bag of water for fish food (less if they are not refrigerated)… and approximately 48 hours in freshwater (provided they are not eaten first), as they are not designed to live in freshwater habitats.

Basically, don’t be too disheartened your Sea Monkey’s die before they have reached half of the lifespan given in the information booklet you got with your new pet.

Keeping Sea Monkey’s Alive!

Being kept in tiny tanks means that the water needs changing more often, as in such a small space, the water deteriorates quickly. Roughly a 20% water change should be done bi-weekly, to ensure clean water and enough oxygen for survival; so that your Sea Monkey’s do not die from suffocation. Adding an aerator into the tank will also keep up oxygen levels, making breathing easier.

Doing a water change with such a small animal can be difficult; ensure you do not accidentally throw away any Sea Monkey’s with the dirty, discarded water! The shedding of the exoskeleton during growth makes up a lot of the dirtiness of the water, with so many of them shedding around the same time!

Causes of Death

Deteriorated, dirty water and lack of oxygen, are common causes of premature Sea Monkey death.The tank being knocked over, and therefore spilling your Sea Monkey’s everywhere, is a big stress to the little creatures, and ultimately will result in the death of the little guys (and girls)! The stress, combined with not being able to breathe out of water… so ensure your Sea Monkey’s are in a safe, secure place where they are unlikely to be knocked over.

Other common causes are the tank being in too warm a location; by a window in summer, in a very warm room/ next to a radiator in winter… or being in a location that makes them too cold; in a room not warm enough in winter, in the fridge because they will be fed to my Comet Goldfish within the week. Of course, being used as food is a cause of death, although this does not apply to Brine Shrimp being kept as pet Sea Monkey’s!

Last Thought

Even though Sea Monkey’s are just simple Brine Shrimp, feel free to imagine them how they were advertised in the 60’s and 70’s (see image, below). – as a cute little family… it may be anthropomorphic, but who doesn’t treat their pet a bit human at times?!

Sea Monkey Family
Sea Monkey Family