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

Hemocoel

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

Hemolymph

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

Carapace

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

Telson

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

Chelicerae

Find & manipulate food, first pair of appendages

Pedipalps

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

Cephalothorax

Possesses the head and leg section of the body

Abdomen

Possesses reproductive, digestive, respiratory and web spinning functions

Book lungs

Specialized respiratory structure

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

Find and manipulate food/specialize into fangs

Fangs

Specialization of chelicerae (terminal end)

Pedipalps

Used primarily to handle food

Tracheal spiracle

Respiration/small apertures on the side of the abdomen

Spinnerets

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

Rostrum

Protects stalked eyes and cerebral ganglia

Antennae

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

Antennules

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

Swimmerets

For females, hold and aerates fertilized eggs

Copulatory swimmerets (male)

Modified swimmeret used for sperm transfer

Seminal receptacle(female)

Receive sperm

Telson

Tail fin, used for propulsion, anus on ventral side

Uropods

Form lateral portions of the tail fin propulsion

Chelipeds

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

Gills

Gas exchange and excretion of nitrogenous wastes

Heart (with ostia)

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

Intestine

Chemical digestion and nutrient absorption

Green glands

osmoregulation

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
-Hemimetabolic
-Holometabolic

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

Ocelli

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

Antennae

Tactile, olfactory and sometimes auditory sensory

Labrum [l??br?m]

Top lip

Mandible

mastication

Maxilla

Food manipulation

Labium [l??b?-?m]

Bottom lip

Spiracles - part of tracheal system

Regulates gas exchange and prevents water loss

Fore/hindwings

flight

Ovipositor

Lay eggs

Tympanum

Detect sound waves that bounce off membrane

Gastric ceca

Secrete digestive enzymes

Testes (male)

Produce sperm

Ovary (female)

Store eggs

Crop

Food storage and digestion with amylase

*Malpighian tubules

Excretory, use to eliminate wastes and osmoregulation

Name the 4 mouth parts of clade insecta

-labrum
-mandible
-maxilla
-labium

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