1. Subphylum Crustacea: Aquatic Mandibulates
Phylum Arthropoda

2. Diversity Over 67,000 species worldwide
Live in aquatic environments (both ocean and freshwater)
Can burrow, creep on bottom of ocean floor
Some are sessile/permanently fixed (barnacles)
Examples include: crabs, crayfish, lobster, shrimp, water fleas, brine shrimp, barnacle, daphnia, fish louse (parasite), krill, pill bugs (rollie pollies)
Called crustaceans

3. Diversity Some are edible (lobster, shrimp, crayfish, crabs)
Others are parasites to other ocean-going organisms
Fill a wide range of ecological roles and have enormous variation
Food, bioindicators, etc
Called Mandibulates
Why? Because of the many pairs of sensory, chewing, food-handling appendages

4. Characteristics of Aquatic Mandibulates
Most have two body regions:
1) Abdomen
Long narrow
Tail region
Includes the telson and uropod

5. Characteristics of Aquatic Mandibulates
Most have two body regions:
2) Cephalothorax
fused head and thorax—chest region,
appendages attached to this
segment
covered by a carapace
Def: a cuticle composed of chitin, protein and calcareous material
Used for protection but is very flexible
Carapace covers most of the cephalothorax

7. Characteristics of Aquatic Mandibulates
Appendages
All appendages are biramous (two main branches)
First two pair:
Antennae (2 pair – this distinguishes them from all other arthropods)
Next pair:
Jaw-like mandibles
Used to chew and crush food
Maxillae
Used to hold food

8. Characteristics of Aquatic Mandibulates
Appendages, cont.
Three pairs of jaw feet called maxillipeds
Used to touch, taste and handle food
Claws for catching food
One pair of walking legs for each segment (four pairs total)
Swimmerets on the abdomen
Used for swimming and to catch sperm

10. Characteristics of Aquatic Mandibulates
Respiration
Gills (if present)
Some use diffusion for respiration
Segments
Most have segments (some have more)
Nervous System
Nerve cord on ventral side that swells to ganglia
Digestive system
Digestive gland mixes food with digestive enzyme
Stomach, intestines, anus

11. Characteristics of Aquatic Mandibulates
Excretory system
Green gland—regulates amount of salt in body
Reproduction
Gonopores—pores that release reproductive cells
The position of these varies according to sex
Location: at the base of a pair of swimmerets or on segments without legs

12. Classification Subphylum Crustacea Class Remipedia Class Cephalocarida
Fairy shrimp
Subphylum Crustacea
Class Remipedia
Class Cephalocarida
Class Branchiopoda
Orders: Anostraca (Fairy Shrimp, Brine Shrimp), Notostraca (tadpole shrimp), Diplostraca (water fleas, clam shrimp)
Brine shrimp
Tadpole shrimp
Water flea

13. Classification Subphylum Crustacea, cont. Class Ostracoda
Fish lice
Subphylum Crustacea, cont.
Class Ostracoda
Class Maxillopoda
Subclasses: Copepoda, Tantulocarida, Branchiura (fish lice), Cerripedia (barnacles)
Class Malocostraca
Orders: Isopoda (pill bug), Amphipoda, Euphasiacea (krill), Decapoda (shrimps, crabs, lobsters)
Copepods

14. Classification Decapods (Order Decapoda)
Crayfish, lobsters, shrimp, crabs
10 walking legs
Carnivores
Eyes on stalks
first three pairs of appendages modified for eating

15. Classification Isopods (Order Isopoda) Pill bugs, sow bugs
Feed on dead, decaying matter
Obtain oxygen from air/moist soil
no carapace
eyes are not stalked
gills on appendages

16. Classification Cerripeds (Subclass Cerripedia) Barnacles
Shelled, sessile
No eyes, gills, heart or blood vessels
Giant Barnacles

17. Classification Copepods Smallest in size Plankton, Krill Feed on algae
No gills or abdominal appendages

18. Crayfish External Dissection

19. Crayfish Characteristics
General Characteristics
freshwater aquatic invertebrate
typically 6 to 8 cm in length, may be as long as 12 cm
jointed exoskeleton
body consists of
cephalothorax and
abdomen

20. Crayfish Characteristics
General Characteristics, cont.
paired, jointed appendages
head has 2 pairs of antennae, 1 pair of mandibles, and 2 pairs of maxillae
undergoes ecdysis (shedding of the exoskeleton to accomplish an increase in body size)

21. Crayfish Characteristics
Digestive System
The digestive tract consists of:
1) the foregut,
includes an enlarged stomach (grinding)
2) the midgut
3) the hindgut (functions in water and salt) regulation.
4) anus
5) digestive gland
secretes digestive enzymes and aids in the absorption of the products of digestion.

23. Crayfish Characteristics
Excretory System
Excretory organs are called the antennal glands
They excrete the waste products of blood filtration;
Ammonia is the primary waste product.
Ammonia is also excreted across the gill surfaces and by diffusion across thin parts of the exoskeleton.

25. Crayfish Characteristics
Respiratory System
Use gills
The gills are located in between the carapace (the exoskeleton of the cephalothorax) and the body wall.
Circulatory System
The circulatory system of the crayfish is centered around a muscular heart

27. Crayfish Characteristics
Nervous System
The crayfish nervous system is composed of a ventral nerve cord
Concentrated ganglia (anterior end)
Giant neurons in the ventral nerve cord function in escape responses.

29. Crayfish Characteristics
Endocrine System
The endocrine glands
Release hormones into the blood
The hormones control functions, such as ecdysis, sex determination, color change and regulation of heart rate

30. Crayfish Characteristics
Sensory Structures
Chemoreceptors
Tactile receptors
function in equilibrium, balance, and position senses
Statocysts
functions in movement and orientation
Ocelli (simple eye)
allows larvae to go toward or away from light
does not form images
Compound eyes
mounted on moveable eyestalks
lens system made of 14,000 individual receptors

31. Crayfish Characteristics
Sexual Characteristics and Reproduction
Crayfish have separate sexes.
Mating occurs just after the female has molted (usually in the spring).
Once they leave their mother, they begin an adult life and reach maturity in anywhere from a few months to a year.
The average life span for a crayfish is two to three years.

32. Crayfish Internal Dissection
Another dissection

33. Crayfish Characteristics
Predator / Prey Relationships
Feed on living animals and plants,
Also consume a fair amount of dead plants, dead or dying animals, and detritus.
Crayfish are omnivores.
Crayfish do not prey on larger animals, such as fish

34. Terrestrial Mandibulates: Spiders and Insects
Phylum Arthropoda

35. Characteristics Segmented bodies Jointed appendages Exoskeleton
Specialized for eating, sensing, reproduction, defense and movement
Exoskeleton
Hard covering on the outside of the animal
Limits the growth of the organism (must shed)
Muscles are attached to this layer
Secreted by underlying epidermis
Shed (molted) at intervals

36. Characteristics Bilateral symmetry Muscular system Body cavity Complex
Contains two types of muscles
Body cavity
Coelom is smaller in size  
Most of body cavity consists of hemocoel (sinuses, or spaces, in the tissues)
Filled with blood

37. Characteristics Digestion Circulatory System Complete digestive system
Esophagus, crop, gizzard, midgut, hindgut and anus
Mouthparts modified from appendages and adapted for different methods of feeding
Circulatory System
Open system
Dorsal contractile heart, arteries

38. Characteristics Respiration Obtain oxygen through:
1) body surface (diffusion),
2) gills,
3) tracheal (air tubes) – carry oxygen to muscles
4) book lungs
Spiracles—small openings in the exoskeleton through which air opens

39. Characteristics Water retention—3 structures 1) Malpighian tubules—
excretory structures that remove metabolic wastes from blood and return water to the cells
2) Exoskeleton—
prevents water evaporation
3) Book Lungs—
gas exchange without water loss (also used in respiration)

40. Characteristics Excretory system Paired excretory glands in some
Same as the nephridial system of annelids 
Some with other excretory organs, called Malpighian tubules

41. Characteristics Nervous system
Contains same system of annelid (with dorsal brain connected by a double nerve chain)
Fusion of ganglia in some species  
Well-developed sensory organs
Compounds eyes with many lenses (can see motion and color)

42. Characteristics Reproduction Sexes usually separate,
Paired reproductive organs and ducts;  
Usually internal fertilization;
often go through metamorphosis (change in body form  larva to adult)

43. Classification Phylum Arthropoda (most diverse phylum)
Subgroups of Terrestrial Arthropods:
Subphylum Chelicerata –
Characteristics of all:
six pairs of appendages that include
a pair of chelicerae,
a pair of pedipalps, and
4 pairs of walking legs
No mandibles and no antennae.  
Suck up liquid food from their prey.
Two body segments (abdomen and cephalothorax)

44. Classification Class Merostomata –
Horseshoe crabs are practically unchanged
Have an unsegmented, horseshoe-shaped carapace, and a broad abdomen, which has a long spine like telson.
Book gills are exposed.  
They feed at night on worms and small mollusks and are harmless to humans.
Include horseshoe crabs

45. Classification Class Arachnida – over 50,000 species
Body organization: cephalothorax, abdomen
Examples: Spiders (35,000 species), scorpions, ticks, mites

46. Classification Spiders: Scorpions: Mites and Ticks:
hunt using strong legs and good eyes; weave silk for web (hunt and reproduction); fangs are modified chelicerae (liquefy prey with venom)
Scorpions:
long, segmented abdomen with a stinger;
Mites and Ticks:
mites have one body segment, eat bacteria or skin cells of humans; ticks are mostly parasitic, require blood before molting and can cause Rocky Mtn spotted fever

47. Classification Subphylum Uniramia – Characteristics:
Appendages are unbranched.  
Includes the insects and the myriapods (centipedes and millipedes).
Heads resemble the crustacean head but have only one pair of antennae, instead of two.
Also have a tympanic membrane for sound 
Have mandibles and two pairs of maxillae
Respiration is by body surface and tracheal systems,
Although juveniles, if aquatic, may have gills.

48. Classification Class Chilopoda -
They are active predators with a preference for moist places such as under logs or stones, where they feed on earthworms, insects, etc.  
Each segment (they have between 10 and 70), except the one behind the head and the last two, bears one pair of appendages.
Include: centipedes

49. Classification Class Diplopoda – Include Millipedes
Have cylindrical bodies made up of 25 to 100 segments.
Abdominal segments each have two pairs.
Millipedes are less active than centipedes
Generally herbivorous, living on decayed plant and animal matter

50. Classification Class Insecta –
Most numerous and diverse of all arthropods.
(There are more species of insects than species in all the other classes of animals combined!!)
Have three pairs of legs
Usually have two pairs of wings (although some have one pair of wings, or none)  
Body organization: head, thorax, and abdomen.
The head usually bears a pair of large compound eyes, a pair of antennae, and usually three ocelli.