Week 6: Clade Arthropoda

Name the 3 clades in arthropoda

Clade Chelicerata
Clade Myriapoda
Clade Crustacea & Clade Hexapoda

Name the 2 clades under Clade Arthropoda, Clade Chelicerata

Clade Merostomata
Clade Arachnida

Name the 2 clades under Clade Arthropoda, Clade Myriapoda

Clade Diplopoda
Clade Chilopoda

Name the 2 clades under Clade Arthropoda, Clade Crustacea

Clade Malacostraca (clade Decapoda is under this)

Name the 6 clades under Clade Arthropoda, Clade Hexapoda (insects)

Clade Orthoptera - grasshoppers, crickets, locusts
Clade Odonata - dragonflies, damselflies
Clade Coleoptera - beetles
Clade Diptera - true flies
Clade Lepidoptera - butterflies, moths
Clade Hymenoptera - ants, bees, wasps

Name characteristics of Arthropoda

� Triploblastic; protostome
� Segments fused into functional groups (tagmata)
� True coelom
� Striated muscles
� Open circulatory system
� Hemocoel
� Hemolymph


� body cavity derived from the blastocoel; expanded portion of the blood system that replaces part


circulating fluid in arthropod of blood & interstitial fluid

What are the 3 key characteristics of Clade Arthropoda

segmented bodies, jointed appendages, exoskeleton

What are the specialized forms of respiration that clade arthropoda uses?

Gills, book lungs/gills, tracheae & spriacles

Characteristics of Clade Arthropoda, Clade Chelicerata, Clade Merostomata (Horseshoe Crab )

� "living fossils"
� Book gills for respiration
� Blue blood is used to test the sterility of medical instruments


Protection/covers the cephalothorax



Cephalothorax (prosoma)

Also called the prosoma, the "head" portion

Gill opercula

Gill protection/hard coverings over the gills

Book gills

Used for respiration and gas exchange, flap-like appendages

Simple eyes (ocelli)

Photoreception/ smaller than the compound eye and set at the midline at the uppermost area of the carapace

Compound eyes

Photoreception, large and set out laterally on the carapace


Aids in anchoring; hard, spiny structure extending posteriorly from the abdomen


Find & manipulate food, first pair of appendages


Assist in movement, specially modified 2nd set of claws appendages


Possesses the head and leg section of the body


Possesses reproductive, digestive, respiratory and web spinning functions

Book lungs

Specialized respiratory structure

Chelicerae [k?-lis??-r?]

Find and manipulate food/specialize into fangs


Specialization of chelicerae (terminal end)


Used primarily to handle food

Tracheal spiracle

Respiration/small apertures on the side of the abdomen


Spinning web/3- paired structures on the end of the abdomen

Characteristics of Clade Arthropoda, Clade Malacostraca, Clade Decapoda (Crayfish)

-5 sets walking legs (1st pair is modified to form pincers-chelae)
-eye on stacks
-include crab, lobster, shrimp


Protects stalked eyes and cerebral ganglia


Paired extension from between the eyes (under the rostrum); longer paired sensory organ


Second paired extension from between the eyes (under the rostrum); shorter paired sensory organ

Compound eyes

Located under rostrum; vision

Carapace covering the cephalothorax

Covers the cephalothorax/ protection


For females, hold and aerates fertilized eggs

Copulatory swimmerets (male)

Modified swimmeret used for sperm transfer

Seminal receptacle(female)

Receive sperm


Tail fin, used for propulsion, anus on ventral side


Form lateral portions of the tail fin propulsion


Predatory function, defense

Walking legs

Biramous, movement

Gastric muscles

Attach from stomach to the carapace

Cardiac stomach

Food storage

Gastric teeth / gastric mill (inside cardiac stomach)

Inside cardiac stomach, mechanical breakdown (mastication)

Pyloric [p�-?l?r-ik] stomach

Chemical breakdown and filtering

Mandibular muscles

Attach from side of stomach to mandible; help masticate


Gas exchange and excretion of nitrogenous wastes

Heart (with ostia)

Pumps blood into hemocoel; blood enters the heart through the ostia


Chemical digestion and nutrient absorption

Green glands


Digestive glands

Secrete digestive enzymes into intestine

How do you differentiate between a female and male clade decapoda (crayfish)

� Look for the seminal receptacle in females
� Look for copulatory swimmerets in males

Characteristics of Clade Insecta

� Uniramous walking appendages
� Tracheal system
� Insect diversity
� Insect adaptability
� Insect social behavior

Characteristics that helped insects thrive on land

o Stronger support systems and walking appendages
o Cuticle
o Internal fertilization
o Specialized respiratory, excretory and digestive structures
o Wings

Hemimetabolic- incomplete metamorphosis (nymph looks like adult)

o Egg --> nymph--> adult

Holometabolic- complete metamorphosis

o Egg--> larva--> pupa --> adult
** Decreases intraspecific competition

Characteristics of Clade Arthropoda, Clade Hexapoda, Clade Insecta (grasshopper)

� Largest class in animal kingdom
� Characterized by 3 pairs of legs and generally 2 pairs of wings
� Tracheal system for efficient respirations

Compound eyes

Image producing eyes that allows sight in almost all diretions around body


Simple photoreceptor composed of numerous ommatidia that create a fairly coarse-grained picture of their visual field


Tactile, olfactory and sometimes auditory sensory

Labrum [l??br?m]

Top lip




Food manipulation

Labium [l??b?-?m]

Bottom lip

Spiracles - part of tracheal system

Regulates gas exchange and prevents water loss




Lay eggs


Detect sound waves that bounce off membrane

Gastric ceca

Secrete digestive enzymes

Testes (male)

Produce sperm

Ovary (female)

Store eggs


Food storage and digestion with amylase

*Malpighian tubules

Excretory, use to eliminate wastes and osmoregulation

Name the 4 mouth parts of clade insecta


How do you differentiate between a female and male grasshopper

o Ovipositor = female

Like annelids, arthropods have three primary germ layers, bilateral symmetry, segmentation and a true coelom. Early arthropods retained these characteristics but added what two additional features? What are the function(s) of each?

� Jointed appendages allows for efficient food handling, movement, and reproduction (include mouth- parts)
� Exoskeleton is made of chitin (insoluble to water) and protects against predation and dehydration; It provides an anchor for muscle attachment, pr

Arthropods were some of the first animals to inhabit land. What challenges were presented by the move from aquatic to terrestrial habitats?

� They need to develop stronger support systems, smaller body size, reproductive, skeletal, digestive, excretory and respiratory systems that conserved water

Arthropods were some of the first animals to inhabit land. What traits were selected for to respond to these challenges?

o Ability to fly (wings)
o Exoskeleton
o Walking appendages
o Cuticle
o Internal fertilization
o Specialized respiratory, excretory and digestive systems
o Various forms of communication and social behavior

Arthropods and vascular plants populated terrestrial habitats simultaneously. Discuss how this affected the relationship(s) between the two.

� Every kind of plant is eaten by one or more species of insects and insects are vectors of pollen for most flowering plants