Subphylum Crustacea

Subphylum Crustacea
Crustacean Characteristics
Have been known and of
economical importance since
ancient times
One of two invertebrates in
the Zodiac
30,000 described living species
From few mm - 4m
Homarus americanus 17 lbs
Found at all depths
Mostly marine and freshwater,
few terrestrial
Some of the largest
morphological diversity =
“insects of the sea”
Class Branchiopoda
-Anostraca ("fairy shrimp"),
Notostraca ("tadpole shrimp"),
Cladocera ("water fleas"),
Conchostraca ("clam shrimp')
- about 800 describes species
- Various aquatic environments
(brackish - fw)
- 0.2-5mm in size (microscopic)
- lifespan of up to a year
- generally filter feeders
- some considered threatened,
used in toxicology
- reproduce parthenogenically
Branchiopod Bauplan
Difficult to generalize
Fused thorax and
abdomen
Apendages =
phyllopodus
# of appendages
varies
Paired compound
and/or single median
eye
Anostraca
Anostraca
Cladocera
Choncostraca
Notostraca
Class Ostracoda
= “mussel shrimp”, 46 species, up to 25mm, up to 1 year
Different lifestyles (parasitic - open water), scavenger,
carnivores or herbivores
Sexual reproduction with larval stages
Paeleontologists = determine habitat & climate condition
Body enclosed in carapace folds, adductor muscle and valves,
antennae/antennules - uniramous
Class Copepoda
Generally up to 20mm
Found on every continent
including Antarctica & in every
ocean
Variety of diets
Free living or parasitic
! Some parasites up to 33 cm
Bioindicator species
Cephalothorax = head &
thorax; abdomen
Antennules = 1st pair
uniramous, 2nd pair varies
Adult females often with egg
sacs
Class Branchiura
About 175 species, example
Argulus
All ectoparasites, fw, coastal
and estuarine, never ocean
=> Important pest in fish
culture
Feed on blood, sucking/rasping
mouth parts
Gonochoristic
Head (carapace), 5 limb
bearing appendages (biramous,
thorax), abdomen
Antennae uniramous
2 suckers, rasping mandibles
Flattened body
Class Cirripedia
= barnacles
1220 species
2.5-30cm, shell color varies
All live attached, marine
Economically detrimental,
invasive
Ectoparasites
Filterfeeders
Gonochoristic
Nauplius and cypris larva
Balanomorpha/Lepadomorpha
Hugely modified body
Softbody surrounded by 6 plates
6 thoraic pair of legs, uniramous
Class Malacostraca
25,000 extant species, most
crustaceans
14 segments + telson and
carapace
Terrestrial, marine, freshwater
Intertidal down to 800 m
Huge size difference = up to
22 kg, 1cm - 4 m
Can endure up to 300 Celsius
Can produce power of 22
caliber bullet (mantis shrimp
tail)
Mostly free living, some
commensals
General Malacostracan Bauplan
7 segments
including telson
8 segments, sometimes
3 segments fused
6 segments
Antennae/antennules
mouthparts
Biramous Appendages
Protopodite
Exopodite
Endopodite
Modified limbs on the thorax of a
crustacean arthropod
Endopodite
Gill
(exopodite)
Endopodite
Gill
Protopodite
(exopodite)
Protopodite
Appendages/mouth parts of a crayfish
1. Walking legs
2. Chelipeds
3. Maxillipeds
4. Gill bailer (second maxilla)
5. First maxilla 7. Antennae
6. Mandibles
8. Antennules