Download 1-2nd antenna 2-compound eye 3-digestive gland 4

Order Cladocera—common name “water fleas”-•a thin bivalve carapace usually enclosing the body except the head, used as a brood chamber
•4-6 flattened leaf-like thoracic appendages with setae used for filter-feeding
•2nd antennae large and used for swimming—a jerky up and down motion
•1st antennae (antennules) small contains sense organs
•no larval stage, newborns resemble adults
•Life cycle alternating between parthenogenesis and sexual stage
1-2nd antenna
2-compound eye
3-digestive gland
4-esophagus
5-heart
6-ocellus eye
7-antennule
8-thoracic (filtering) legs
9-ovary
10-anal claws (furca)
11-postabdomen
12-brood chamber
13-carapace
14-rudder bristle
15-tail spine
http://www.cladocera.de/cladocera/cladocera.html
Fecal pellets
Zooplankton such as Daphnia filter-feed using currents generated by
their thoracic appendages. Fecal pellets sediment rapidly to the bottom
Male cladocera are usually produced from
parthenogenetic eggs under adverse environmental conditions
Males are usually much smaller than females
have a reduced beak (rostrum), no brood chamber
•elongated antennule
•A grasping appendage with a hook
•after being fertilized by a male the female
produces an ephippial egg in her brood chamber
Ephippial eggs are special resistant eggs that have a resistent coat made from the brood pouch. They can lie
dormant in the mud for months or sometimes even years.
http://images.google.ca/imgres?imgurl=http://www.microscopyuk.org.uk/mag/imgmar02/daphnia_male.jpg&imgrefurl=http://www.microscopy
uk.org.uk/mag/artmar02/waterfleamale.html&h=450&w=321&sz=33&hl=en&start=2&tbnid=56Ssww0b39aoM:&tbnh=127&tbnw=91&prev=/images%3Fq%3Dmale%2Bdaphnia%26svnum%3D10%26hl%3Den%26lr%3D%26sa%3DG
Asexual (parthenogenesis) alternating with sex
Meiosis
Bosminidae--Bosmina
First antennae large, extending forward from the rostrum in the form of a tusk
Chydoridae, Chydrorus—carapace
projecting forward into a blunt rostrum
and covering the head with a shield.
Daphniidae, Ceriodaphnia—head small and
depressed, rostrum absent, cervical sinus
present
Polyphemidae, Polyphemus
Note that the carapace covers only the brood chamber and not the thoracic
appendages, tail spine fairly long
A predator on small zooplankton
Note the carapace
covers only the brood
sac and not the
swimming legs
This is a predator on
other zooplankton
Around 10 mm long
The tail spine is very
long, with a series of
barbs—protection from
predation by small fish
Another Polyphemid, Bythotrephes—an exotic invader from Asia.
Note the forward projecting head
shield of the carapace
Very large postabdomen and anal claw
Eurycercus—a large (>5mm) littoral chydorid
Crawls around on vegetation and feeds on epiphytes mainly
Chydorid cladocera
feeding on epiphytes
from submerged
macrophytes
http://www.hi.is/~arnie/ecercus.gif
Leptodora
Polyphemus
Holopedium
Sida
Polyphemus
Diaphanosoma
Leptodora
Polyphemus
Holopedium
Leptodora
Sida
Diaphanosoma
Holopedium
Sida crystallina
Diaphanosoma
Chydoridae
Daphnidae
Chydoridae
Bosminidae
Macrothricidae
Moinidae
Bosminidae
Daphnia
Ceriodaphnia
Scapholeberis
Simocephalus
Simocephalus
Daphnia
Ceriodaphnia
Scapholeberis
Simocephalus
Scapholeberis
Daphnia
Ceriodaphnia
Scapholeberis
Simocephalus
Order Notostraca—”shield shell” (3-4cm)
•Common name tadpole shrimp, 12 species
•Cephalothorax covered by a large shield-like
carapace
•1st antenna small uniramous, 2nd antenna
reduced or absent, maxillipeds absent
•, the 1st pr thoracic appendages enlarged and
protruding from under the carapace
•next 10pr thoracic appendages phyllopodous
(leaf-like) swimming/feeding legs, plus many
smaller appendages on the abdomen
•Telson with 2 long whip like caudal rami
•Can be either dioecious, hermaphrodites or
parthenogenetic, most often the latter.
•Freshwater, brackish or saline temporary
ponds, shallow, fishless lakes, omnivores
•Worldwide distribution, some species are
pests in rice paddies, others are endangered
species
•Well adapted to temporary ponds because
their eggs can diapause and dry up completely
•“living fossils” a fossil record extends back
350 million years (Devonian)
•Two genera Triops and Lepidurus
A. Dorsal anatomy
Note the three eyes, 2 compound, and
median ocellus, and the depressions for
the maxillary gland
B. Ventral anatomy
C. The maxilla
D. Thoracic appendage used for swimming
and channeling food to the mouth
http://www.cst.cmich.edu/users/mcnau1as/zooplankton%20web/Triops/images/triops.jpg
Triops cancriformis—the oldest extant species on the planet
The modern species is identical to fossils identified from the Triassic
http://www.aquarienclub.de/pics/triops_cancriformis.jpg
Triops, resting egg
Day 1, metanauplius
Day 3 shield present
Day 6 subadult
Day 2 metanauplius
Adult Triops 2-3 weeks
The eggs can survive drying and freezing and
can last in dried up ponds for decades
Temporary pond habitat
http://www.cst.cmich.edu/users/mcnau1as/zooplankton%20web/Triops/images/triops.jpg
Order Anostraca—without hard shell (1-15cm)
•Common name “fairy shrimp”, “brine shrimp”
•Body soft and flexible, not covered by a shell
•1st & 2nd antennae uniramous, sometimes
prehensile
•>11pr of phyllopodous (leaf-like)
swimming/feeding legs on the thorax
•Usually dioecious, except some brine shrimp
which are parthenogenetic
•Freshwater, brackish or saline temporary ponds,
shallow, fishless lakes, omnivores or carnivores
•Worldwide distribution
•Well adapted to temporary ponds because their
eggs can diapause and dry up completely
•“living fossils” a fossil record extends back 500
million years
•8 families eg
•Artemidae
•Branchinectidae
•A few dozen spp.
Artemia—the brine shrimp found in hypersaline inland waters eg the Dead Sea or the
Great Salt Lake, Utah.
Artemia showing the
extended distal “blade” of
the second antenna
Most Artemia are parthenogenetic females, but some populations are dioecious
Order Conchostraca—”clam shell” (1-15cm)
•Common name “clam shrimp”,
•With a dorsally hinged bivalved carapace
completely enclosing the head and body,
including the legs
•1st antennae uniramous, 2nd antennae biramous
•>11pr of phyllopodous (leaf-like)
swimming/feeding legs on the thorax
•Dioecious or parthenogenetic
•Freshwater, brackish or saline temporary ponds,
shallow, fishless lakes
•Filter feeders/ omnivores
•Worldwide distribution
•Well adapted to temporary ponds because their
drought resistant eggs
•fossil record extends back to the Devonian
•7 families, >30 spp
•Eg Lynceidae
Lynceus is a common Conchostracan in Alberta
http://animaldiversity.ummz.umich.edu/site/resources/Grzimek_inverts/Conchostraca/Lynceus_gracilicornis.jpg/me
dium.jpg
http://crustacea.nhm.org/peet/conchostraca/media/morph.jpg
Hypothesized evolutionary relationships of the various Branchiopod orders
These Crustacea were abundant in the sea long before terrestrial and inland water habitats were
colonized by plants and animals. Why do you think they have survived much longer than most
other Paleozoic animal groups