ZOO 115 Invertebrate Zoology

Phylum Arthropoda

Subphylum Chelicerata

Subphylum Chelicerata

Includes spiders, horseshoe crabs, seas spiders and scorpions

Have only two tagmata: cephalothorax and the abdomen

Cephalothorax

Abdomen

Subphylum Chelicerata

Cephalothorax bears 6 pairs of appendages

Chelicera are on the 2nd cephalothorax segment

Pedipalps 4 pr walking legs. Do not have

antennae and deutocerebrum

Abdomen has 12 or fewer segments

Pedipalp

Chelicerae

Subphylum ChelicerataClass Xiphosura

Horseshoe crabs Up to 75 cm (largest

chelicerates) Live in marine shallow

water on soft bottoms Omnivores Toxic (lethal) to Predators

– saxotoxin in tissues Vestigial coelom = body

cavity is hemocoel

http://www.globalclassroom.org/hcrab2.jpg

http://mainegov-images.informe.org/dmr/rm/aquarium/teachers_guide/horseshoe_crab_dorsal_view.jpg

Telson

Carapace

Compound eye Median eyes

Subphylum Chelicerata Class Xiphosura - Anatomy

6 pair of appendages 1 pr

Chelicera 4 pr chelate

legs 1 pr pusher

legs

Chelate walking legs

Pusher leg

http://mainegov-images.informe.org/dmr/rm/aquarium/teachers_guide/horseshoe_crab_dorsal_view.jpg

Subphylum ChelicerataClass Xiphosura - Feeding Uses chelate

walking legs and chelicera to capture food.

Transferred to the food groove

Base of appendages are grinding surfaces (gnathobases)

Spines on appendages move food to mouth

Gnathobase

Mouth

Food

Subphylum ChelicerataClass Xiphosura - Feeding

Mouth to crop Transferred to

muscular toothed gizzard

Moves to stomach Digestable material

to digestive pouch Other material to

intestine Solid waste outside

via anus

http://mainegov-images.informe.org/dmr/rm/aquarium/teachers_guide/horseshoe_crab_internal_anatomy.jpg

Food

Crop

StomachGizzard

Digestive pouch

Solid waste

Intestine

Subphylum Chelicerata Class Xiphosura - Gas Exchange

Water moves in through space between the abdominal plate and the carapace

http://mainegov-images.informe.org/dmr/rm/aquarium/teachers_guide/horseshoe_crab_internal_anatomy.jpg

Gills Then moves across gills and out

Subphylum Chelicerata Class Xiphosura - Circulation

Blood flows into heart (via ostia)

http://mainegov-images.informe.org/dmr/rm/aquarium/teachers_guide/horseshoe_crab_internal_anatomy.jpg

Pericardial sinusHeart

Pumped through arterial system

Back to heart

Into hemocoel

Through gills

Subphylum ChelicerataClass Xiphosura – Nervous system

Large brain Compound lateral eyes Pair of median pigment cup ocelli Rudimentary ventral eye Sensilla

mechanoreceptors chemorecepetors osmoreceptors

Subphylum ChelicerataClass Xiphosura – Reproduction

Gonochoric Sexual dimorphic – male

smaller Mating during exceptionally

high tides of full and new moons during Spring and Summer

Female deposits 2000-30000 eggs into sand

Male fertilizes eggs Have a trilobite larva http://www.lander.edu/rsfox/310limulusLab_files/image020.jpg

Subphylum Chelicerata – Class Arachnida

Includes spiders, scorpions, mites and ticks

~70,000 described sp. but maybe a million more

Mostly carnivores

Subphylum ChelicerataClass Arachnida - Anatomy

Appendages Cheliceae

Sometimes with poison or silk

Pedipalps Many

functions

4 pr walking legs http://www.rochedalss.eq.edu.au/spider/spideran.gif

Pedipalp

Chelicera

CheliceraPedipalp

Subphylum ChelicerataClass Arachnida - Digestion

Small digestive tube

Digestion starts in preoral cavity formed by appendages and carapace- proteolytic enzymes

Either the stomach or pharynx is a muscular pump http://www.rochedalss.eq.edu.au/spider/spideran.gif

Subphylum ChelicerataClass Arachnida –Circulation

Trachae Book lungs

Subphylum ChelicerataClass Arachnida – Gas Exchange and circulation Gas Exchange

Trachae Book lungs

Circulation Hemocoel Book lungs Heart Arterial

system Back to

hemocoelhttp://www.sci.sdsu.edu/classes/bio201/book%20lung.gif

Subphylum ChelicerataClass Arachnida – Excretion

Excrete quanine, adenine, xanthine or uric acid Allows little loss of water

Two systems Nephridia Malphigian tubules

Subphylum ChelicerataClass Arachnida – Nervous system

http://instruct1.cit.cornell.edu/courses/bionb424/students2004/leb27/CNSsmall.jpg

Brain

Subphylum ChelicerataClass Arachnida – Nervous system

Sensory Compound eyes – small but greater number Sensory setae – major sense organs

Mechanoreceptors Trichbothria – specialized for sensing weak air

movement. Chemoreceptors

Slit sense organs – strain gauges for cuticle No antennae but often equivalent on legs

Class Arachnida - Diversity

Order Scorpiones 3-21 cm in length Greatly enlarged

pedipalps Very small

chelicerae Stinger Predators – stay

near burrowhttp://www.regalreptile.com/scorpion%203.jpg

http://www.thedailylink.com/thespiralburrow/anatomy/anat02.html

Can sting within 0.75 sec.

Class Arachnida - Diversity

Order Scorpiones Gonochoric

Mature – 6 yrs Extended courtship

ritual Indirect sperm transfer

– spermatophores Viviparous Care of young Direct development –

months Live up to 25 yrs

http://www.regalreptile.com/scorpion%203.jpg

http://www.thedailylink.com/thespiralburrow/anatomy/anat02.html

http://cals.arizona.edu/pubs/insects/az1320/Female-bark-scorpionalt.jpg

Class Arachnida - Diversity

Order Uropygi Whip scorpions or

Vinegaroons 80 mm in length Cephalothorax

completely covered by carapace

Pair anterior median eyes

3-4 pairs lateral eyes Small chelicerae Large chelate pedipalps

http://www.petbugs.com/caresheets/gallery/M-giganteus.jpg

Class Arachnida - Diversity

Order Uropygi 2 pair book lungs Pair of large

repugnatorial glands 84% acetic acid and 5%

caprylic acid 1st leg acts as

antennae Gonothropic

Complex courship Indirect sperm transfer -

spermatophore

http://www.petbugs.com/caresheets/gallery/M-giganteus.jpg

Class Arachnida – DiversityOrder Amblypygi

Whip spider 1st legs – antennae All legs sensory Anatomy similar to spiders:

Chelicerae similar to spiders but lack poison glands. repugnatorial glands

No silk produced Tends to move laterally Indirect sperm transfer -

spermatophore

http://www.amnh.org/exhibitions/hall_tour/spectrum/specimens/a2395h.jpg

Class Arachnida – DiversityOrder Araenae Spiders 0.5 mm to 9 cm in length ~40,000 described sp, ~130,000

undescribed sp. Males usually smaller than females Three groups based

Most Primitive Primitive chelicerae (only

longitudinal movement) Segmented abdomen

Primative Primitive chelicerae

Advanced Fangs can move to oppose each

other

Class Arachnida – DiversityOrder Araenae – Silk What is it?

Made of glycine, alanine and serine 6-8 different kinds

5-6 used by any one spider 0.003 mm thick

Produced by Silk glands – different kinds Spinnerets

Single thread composed of many fibers which are weaved together Cribellum – not in all

Anterior to spinnerets Fine silk used for prey capture

Spiders eat silk to reclaim it

Silk glands Spinnerets//www.astrographics.com/GalleryPrints/Display/GP2017.jpg

http://www.dmns.org/main/minisites/spiders/idkey1.html

Cribellum

http://www.dmns.org/main/minisites/spiders/idkey1.html

http://www.museums.org.za/bio/spiderweb/reproduction.htm

Class Arachnida – DiversityOrder Araenae – Silk Function

Reproduction Sperm web Egg case Nests

Dragline Dispersion Prey capture (webs)

http://typhoon.wcp.muohio.edu/tropicalvideos/costarica03/spidereggcase03.jpg

http://www.washington.edu/burkemuseum/spidermyth/images/draglinethumb.jpg

http://citybugs.tamu.edu/FastSheets/images/spider-ballooning.gif

Class Arachnida – DiversityOrder Araenae – Prey capture Web builders

Orbs Only the spiral is sticky Walk on radial Built to catch specific

types of insects Affected by food

Tunnel or Trapdoor

http://www.nancylynne.com/Spider%20Web%20for%20web.jpg

http://www.coffee.co.uk/spiders.html

http://www.1000plus.com/alex/ImageGallery/Arachnids%20-%20Spiders/tn/Tunnel%20Spider.jpg.html

Tarantula

http://mamba.bio.uci.edu/~pjbryant/biodiv/spiders/Aphonopelma%20reversum.htm

http://www.bushveld.co.za/pictures-arachnids/garden-spider-large.jpg

Hunting Heavier legs Good eyes in many

http://research.amnh.org/entomology/blackrock2/images/main_key/scopulae_philodromidae.gif

Class Arachnida – DiversityOrder Araenae – Prey capture

Scopulae – walk up walls or glass

http://www.dal.ca/~egingl/research.htm

Best developed slit sensors on legs- vibration

http://dine.sanjuan.k12.ut.us/heritage/land/animals/bugs/images/wolf_spider.jpg

Eyes Main Secondary

Class Arachnida – DiversityOrder Araenae – Prey capture

Fangs Movement http://www.geocities.com/spiders_snakes/spider/fang.jpg

http://static.howstuffworks.com/gif/spider-fang.gifhttp://www.museums.org.za/bio/spiderweb/bites.htm

Hunters – cytotoxin antibiotics usually required no anti-venom anti-tetanus injection Some patients

In 3 days mild fever, headaches

The above victim saw the Brown Recluse spider on her foot as she got out of the shower. This leg no longer exists because she had to have it amputated below the knee.

http://www.brown-recluse.com/index.html?google1

Brown Recluse or Violin spider

Toxin

Class Arachnida – DiversityOrder Araenae – Prey capture

Fangs Movement

Web-builders – neurotoxin severe pain in the chest

and abdomen anxiety, raised blood

pressure breathing difficulties and

heart palpitations nausea and vomiting sweating, excessive

salivation and watery eyes a rash might develop

Toxin

Black Widow

http://library.thinkquest.org/C007974/media/2_4bla.jpg

http://www.dobrodruh.cz/data/bookimg/00363-atrax.jpg

AtraxFunnel-Web spiderLETHAL

http://acd.ufrj.br/mndi/Aracnologia/Trechona.htm

TrachomaFunnel-Web SpiderLETHAL

Class Arachnida – DiversityOrder Araenae – Prey capture

Fangs Movement

Non-Toxic

http://www.ambergriscaye.com/pages/photos/art/tarantula.jpg

Class Arachnida – DiversityOrder Araenae – Digestion

Either totally dissolve prey with enzymes or masticate

Fluid sucked into midgut passing through particle filters

Digested in Caeca

Class Arachnida – DiversityOrder Araenae – Gas Exchange

Book lungs And/or tracheae

Class Arachnida – DiversityOrder Araenae – Reproduction

Gonochoric Indirect sperm

transfer No spermatophores Transferred by

pedipalps

Male spins sperm web (shown earlier)

Deposits sperm on web

Transfers sperm to pedipalps

Pedipalps transfer sperm to female

Class Arachnida – DiversityOrder Solifugae

Sun spider ~800 species 2 mm – 7 cm Inhabit warm arid regions Enormous chelicerae No venom 1st legs used as antennae Males extremely fast

Highly developed tracheae

http://www.key-net.net/users/swb/pet_arthropod/SS.jpg

Class Arachnida – DiversityOrder Opilones

Daddy long-legs or Harvestman

~5000 species 5 mm – 22 cm body No venom No constriction between

cephalothorax and abdomen

Long legs because of a multisegmented tarsus May have 100s

Eyes on Tuberclehttp://www.thelensflare.com/large/spider_979.jpg

http://www.xs4all.nl/~ednieuw/Spiders/Info/spiderinfo.htm

Spider leg

http://troyb.com/photo/images/photos/00012918.jpg

Class Arachnida – DiversityOrder Acari

Ticks and mites ~40,000 described

>1,000,000 undescribed 0.1 – 0.75 mm length

Smallest can live in tracheae of honeybee

Present in all habitats tagmata different No segmentation Entire body covered with

single carapacehttp://www.uky.edu/Agriculture/Entomology/entfacts/struct/amdogtik.gif

Gnathosoma

Idiosoma

http://www.sdm.buffalo.edu/scic/toms_tick/tick-2_full.jpg

Pedipalp

Class Arachnida – DiversityOrder Acari

Large diversity in feeding Carnivores Herbivores Scavengers Ectoparasites Endoparasites

http://www.uky.edu/Agriculture/Entomology/entfacts/struct/amdogtik.gif

http://www.ijon.de/zecken/images/i-hex-wg.gif

Chelicera

Pedipalp

Class Arachnida – DiversityOrder Acari

Nervous system Sensory setae

Air currents Heat Chemo Mechano

Median and lateral eyes

Slits on legs that may be analogous to slit sense organs http://www.uky.edu/Agriculture/Entomology/entfacts/

struct/amdogtik.gif

Class Arachnida – DiversityOrder Acari

Reproduction Gonochoric Indirect sperm transfer

by spermatophore Transferred by

chelicera, male 3rd pr. legs or female may pick up.

Eggs in soil or humus 2-6 wk incubation

http://www.uky.edu/Agriculture/Entomology/entfacts/struct/amdogtik.gif