How To Guess the Age Of Platycryptus Undatus

[Nicole C G]

Here’s something I’ve observed that seems to be a pretty good way of telling their age at this point.

If you are trying to guess the age of a Platycryptus undatus jumping spider, you may be trying to look at it’s size and like most jumpers, the size can vary a lot by geographic location, gender, or even just the individual. But here’s something I’ve observed that can help. I will add sizes (body not legspan) in my area as a frame of reference, but not a fact for all undatus.

The main way I can tell is a hexagon shaped head. Adults both male and female adults have these hexagon shaped heads.

male 1.2cm

female 1.5cm

And the more hexagonal the head the older they are until they eventually become adults.
Here is a very young juvenile. 3mm. Notice it’s head? It is a round shape. It is this same shape for a long time until they get closer to adulthood.


This next juvenile is a few molts ahead of the last one. It was 5mm. This is actually my pet Mori the day I found it.

Mori 5mm. Still the round shaped head.

The next is an older juvenile at 7mm notice the head is starting to get more hexagonal? The legs also get fluffier as they age.

Juvenile 7mm

And finaly, what I believe to be a sub-adult female. The shape of the head is almost fully hexagonal, but not quite.

Female sub adult or 1molt till. 1cm (ate a lot)

the hexagonal shape is a good way to tell the age of platycryptus undatus. Also for those wondering, to tell the difference between adult male and adult female, females have a white stripe under their eyes, and males have an orange stripe.

I’m still unsure at what stage they get their orange stripe.

If anyone wants to add anything please tell me

 

[Nicole C G]

Note: I was over measuring them at the time. So true sizes were 5-3mm smaller than stated. (Except for Mori which was actually 5mm and the sling which was 2.5mm)

Also, here is Mori’s head shape now two molts later

 

[egyptiancrow]

males get orange on their face in addition to white/grey at subadult and only adults have full orange stripes and their fully pedipalps and long arms.


older males seem to suffer quite a lot from being unable to stick to acrylic or glass and fall often.
if theres any missing patches of hair /their black skin showing through it also shows wear and tear.
other than this you really need to just know the spiders history. why captive breeding is so important for pets. otherwise you are left in the dark.

but i hope this helps
ive raised many myself

 

[Nicole C G]

males get orange on their face in addition to white/grey at subadult and only adults have full orange stripes and their fully pedipalps and long arms.


older males seem to suffer quite a lot from being unable to stick to acrylic or glass and fall often.
if theres any missing patches of hair /their black skin showing through it also shows wear and tear.
other than this you really need to just know the spiders history. why captive breeding is so important for pets. otherwise you are left in the dark.

but i hope this helps
ive raised many myself

Are you sure they only get the orange stripe at sub adult? I feel like I’ve seen some males that looked penultimate with the orange stripe. Thank for your reply!

 

[egyptiancrow]

Are you sure they only get the orange stripe at sub adult? I feel like I’ve seen some males that looked penultimate with the orange stripe. Thank for your reply!

yes, 100% sure. subadults can only have a flash of orange, but dont get the whole stripe until theyre an adult.

some older males might have some of their hair rubbed off or be a slightly different color (ive seen a lot of darker or mottled ones in the north and south east coast) which might make their pedipalps look nubbier which may make them seem younger but in fact theyre elderly.

 

[Nicole C G]

yes, 100% sure. subadults can only have a flash of orange, but dont get the whole stripe until theyre an adult.

some older males might have some of their hair rubbed off or be a slightly different color (ive seen a lot of darker or mottled ones in the north and south east coast) which might make their pedipalps look nubbier which may make them seem younger but in fact theyre elderly.

Thank you! That helps a lot for identifying.