Feature Journal

The Lock and Key of Spiders

15 September 2012
In the reproduction of spiders, the male typically transfers it’s sperm from it’s pedipalps to the female’s epigyne. The epigyne is the external genital structure of female spiders located on the underside of the abdomen, while the pedipalps of a male spider resemble miniature legs with the palpal organ in the last segment that is used for the sperm transfer.

The structure of the epigyne and the palpal organs vary so greatly in it’s form across different species that they often provide the most distinctive characteristic for identifying different spider species. Because of that, I’d usually term these two organs the lock and key.

Lynx Spider (Oxyopidae) - IMG_5632#1 The enlarged black pedipalps of a sexually mature Lynx Spider (Oxyopidae) are so distinct that some called them boxing gloves

Crab Spider (Thomisidae) - DSC_5142#2 The epigyne of this female Crab Spider (Thomisidae) is the brown spot located on the abdomen, near to the carapace. That is where the male crab spider would position it’s pedipalps

Crab Spiders mating (Thomisidae) - DSC_7452#3 The actual mating position, where the tiny male crab spider clings onto the female like a baby

Big-Bellied Tylorida Spiders (Tylorida ventralis) - DSC_3787#4 This pair of Big-Bellied Tylorida Spiders (Tylorida ventralis) are just doing it at their own pace while flattened on a tree branch

Huntsman Spiders (Sparassidae) - DSC_3636#5 The pedipalps of a male Huntsman Spider (Sparassidae) are long enough to reach the female’s epigyne while the male is on top. This picture does not show the connection yet.

Sometimes, the same spider species may have slightly different morphological structures. The epigyne or pedipalps would then be used to verify if they are indeed from the same species. Some taxonomists might disagree, but this is the most recognized method so far.

Crab Spider (Thomisidae) - DSC_5133#6 Here’s the front view of the Crab Spider from above. Not too happy that I took a pic of her genitalia!! (oops)

Crab Spider (Thomisidae) - DSC_5128#7 Top view. Also known as the dorsal view.

Crab Spider (Thomisidae) - DSC_5126#8 Another view of it’s grumpy face

Spitting Spider (Scytodidae) - DSC_5101#9 Spitting Spider (Scytodidae), the body parts usually remind me of watermelons… hmmm…

Spitting Spider (Scytodidae) - DSC_5115#10 Side view. Also known as the lateral view.

Spitting Spider (Scytodidae) - DSC_5100#11 View from the front. This spider captures prey by spitting a venomous sticky fluid before biting and wrapping it up with silk

Wolf Spider (Lycosidae) - DSC_5096#12 One of the tiny Wolf Spiders (Lycosidae) on the ground. Has a slight tinge of blue, but appears black from the naked eye

Sac Spider (Clubionidae) - DSC_5094#13 Sac Spider (Clubionidae), very distinct row of 6 eyes

Sac Spider (Clubionidae) - DSC_5092#14 Top view of the Sac Spider

Orbweaver Spider - Argiope sp. - DSC_5090#15 Juvenile Argiope sp. with prey

Gecko - DSC_5087#16 Cute little gecko

Gecko - DSC_5086#17 Lazy to change my setup on the spot so I only have close ups of this fella

Whip Scorpion (Thelyphonida) - DSC_5235#18 The resident of this area – Whip Scorpion (Thelyphonida)

Centipede - DSC_5230#19 Close up on a centipede, with tiny mites on the antennae

Centipede - DSC_5228#20 Slightly wider view to show the red legs

Crab Spider (Thomisidae) - DSC_5226#21 Crab Spider (Thomisidae), doesn’t look like the common crab spiders

Crab Spider (Thomisidae) - DSC_5249#22 Front view

Crab Spider (Thomisidae) - DSC_5242#23 Dorsal view

Crab Spider (Thomisidae) - DSC_5240#24 Lateral view

Wandering Spider (Ctenidae) - DSC_5219#25 One of the many Wandering Spiders (Ctenidae) on the forest floor

Malesian Frog (Limnonectes malesianus) - DSC_5212#26 Malesian Frog (Limnonectes malesianus)

Malesian Frog (Limnonectes malesianus) - DSC_5203#27 Malesian Frog (Limnonectes malesianus)

Liocranidae - DSC_5197#28 One of the more bizarre finds of the night, possibly a Liocranid hiding in it’s burrow. It had a lid to cover the burrow when we approached!

Liocranidae - DSC_5186#29 After the burrow entrance was sealed, it was virtually impossible to locate the burrow

#30 Took a video to show how the spider closed it’s burrow. Handheld with Raynox, beware of jittery video!

Assassin Bug Molt (Reduviidae) - DSC_5183#31 Moult of an Ant-Snatching Assassin Bug

Assassin Bug Molt (Reduviidae) - DSC_5179#32 Flipped it over for a view of the underside

Harvestman (Opiliones) - DSC_5178#33 Harvestman (Opiliones) eating a fungus

DSC_5173#34 Not sure of ID…

Nursery Web Spider (Pisauridae) - DSC_5162#35 Could be a Pisaurid or Ctenid, needed a better view of the eyes to confirm

Huntsman Spider (Sparassidae) - DSC_5176#36 Huntsman Spider (Sparassidae)

Huntsman Spider (Sparassidae) - DSC_5160#37 Beautiful patterns on this Huntsman Spider!

Huntsman Spider (Sparassidae) - DSC_5158#38 Record shot of the dorsal view

Nursery Web Spider (Pisauridae) - DSC_5156#39 ID also not determined yet

Nursery Web Spider (Pisauridae) - DSC_5152#40 ID also not determined yet

DSC_5146#41 Another juvenile Argiope sp.

Araneus sp. - DSC_5163#42 Araneus sp. Probably a Kidney Garden Spider.

Comb-footed Spider (Theridiidae) DSC_5079#43 Comb-footed Spider (Theridiidae), this is usually found in curled up leaves

DSC_5164#44 Orb Weaver Spider (Araneidae)

Orb Weaver Spider (Araneidae) - DSC_5074#45 Araneus sp.

DSC_5168#46 One of the many spiders on it’s web

Twig-like feather-legged spider (Miagrammopes sp.) - DSC_5237#47 Twig-like feather-legged spider (Miagrammopes sp.)

Nursery Web Spider (Pisauridae) - DSC_5147#48 Last shot of the mysterious spider with ID yet to be determined

The full album can be viewed here.



Hi my name is Nicky Bay. I am a macro photographer, instructor and book author, travelling the world to document the vast micro biodiversity that nature has to offer. Follow my updates and discover with me the incredible beauty and science behind our planet's micro creatures!

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