1. Chapter 36 Table of Contents Section 1 Phylum Arthropoda
Arthropods
Table of Contents
Section 1 Phylum Arthropoda
Section 2 Subphylum Crustacea
Section 3 Subphylum Chelicerata and Myriapoda

2. Section 1 Phylum Arthropoda
Chapter 36
Objectives
Describe the distinguishing characteristics of arthropods.
Explain the process of molting in an arthropod.
List the five major subphyla of the phylum Arthropoda.

3. Characteristics of Arthropods
Section 1 Phylum Arthropoda
Chapter 36
Characteristics of Arthropods
The members of the phylum Arthropoda are called arthropods.
Arthropods are segmented animals with body segments that bear appendages.
Arthropods have an exoskeleton that provides protection and support and contains chitin.
Arthropods show a high degree of cephalization. Most have segmented antennae and compound eyes.

4. Chapter 36 Segmentation Section 1 Phylum Arthropoda
Click below to watch the Visual Concept.
Visual Concept

5. Chapter 36 Compound Eye Section 1 Phylum Arthropoda
Click below to watch the Visual Concept.
Visual Concept

6. Function of the Compound Eye
Section 1 Phylum Arthropoda
Chapter 36
Function of the Compound Eye
Click below to watch the Visual Concept.
Visual Concept

7. Characteristics of Arthropods, continued
Section 1 Phylum Arthropoda
Chapter 36
Characteristics of Arthropods, continued
Molting
The rigid exoskeleton limits the size to which an arthropod can grow.
So, each arthropod periodically sheds its exoskeleton and makes a new one in the process of molting.
An anthropod goes through many cycles of molting during its life.

8. Characteristics of Arthropods
Section 1 Phylum Arthropoda
Chapter 36
Characteristics of Arthropods

9. Characteristics of Arthropods
Section 1 Phylum Arthropoda
Chapter 36
Characteristics of Arthropods
Click below to watch the Visual Concept.
Visual Concept

10. Arthropod Exoskeleton
Section 1 Phylum Arthropoda
Chapter 36
Arthropod Exoskeleton
Click below to watch the Visual Concept.
Visual Concept

11. Evolution and Classification
Section 1 Phylum Arthropoda
Chapter 36
Evolution and Classification
Arthropods likely evolved from a common ancestor that lived about 545 million years ago.
However, biologists are still uncertain about much of arthropod phylogeny.
The similar characteristics of many modern subgroups of arthropods may be the result of convergent evolution.

12. Evolution and Classification, continued
Section 1 Phylum Arthropoda
Chapter 36
Evolution and Classification, continued
Many ancient and extinct arthropods, such as trilobites, had many body segments and one pair of appendages on each segment.
Most living arthropod species have some segments that lack appendages and some segments that are fused into a larger structure called a tagma (plural, tagmata).

13. Evolution and Classification, continued
Section 1 Phylum Arthropoda
Chapter 36
Evolution and Classification, continued
Arthropods are usually divided into five subphyla on the basis of differences in development and in the structure of appendages, such as mouthparts.
The two major types of mouthparts are:
mandibles, which are jawlike
chelicerae (singular, chelicera), which are pincerlike
The five main subphyla are:
Trilobita
Crustacea
Chelicerata
Myriapoda
Hexapoda

14. Phylogenetic Diagram of Arthropods
Section 1 Phylum Arthropoda
Chapter 36
Phylogenetic Diagram of Arthropods

15. Chapter 36 Types of Arthropods Section 1 Phylum Arthropoda
Click below to watch the Visual Concept.
Visual Concept

16. Chapter 36 Objectives Describe the characteristics of crustaceans.
Section 2 Subphylum Crustacea
Chapter 36
Objectives
Describe the characteristics of crustaceans.
Compare aquatic crustaceans with terrestrial crustaceans.
Explain the functions of the appendages on a crayfish.
Summarize digestion, respiration, circulation, excretion, and neural control in crayfish.

17. Chapter 36 Characteristics
Section 2 Subphylum Crustacea
Chapter 36
Characteristics
The subphylum Crustacea contains about 38,000 known species.
Crustaceans are so diverse that their single defining characteristic is having two pairs of antennae.
Most crustaceans also have:
a pair of mandibles
a pair of appendages on each body segment
some branched appendages
16 to 20 segments and several tagmata

18. Characteristics, continued
Section 2 Subphylum Crustacea
Chapter 36
Characteristics, continued
Some crustaceans respire through their exoskeleton, others respire through gills.
Many have a free-swimming larval stage called a nauplius.

19. Chapter 36 Anatomy of a Nauplius Section 2 Subphylum Crustacea
Click below to watch the Visual Concept.
Visual Concept

20. Diversity of Crustaceans
Section 2 Subphylum Crustacea
Chapter 36
Diversity of Crustaceans
Aquatic Crustaceans
Copepods are abundant in marine environments and an important part of the ocean’s plankton.
In freshwater environments, much of the plankton is composed of water fleas such as Daphnia species.
Barnacles are sessile as adults.
Free-swimming barnacle larvae attach themselves to marine surfaces and develop a shell that encloses the body.
Barnacles use their cirri (singular, cirrus) to sweep food from the water into their mouths.

21. Diversity of Crustaceans, continued
Section 2 Subphylum Crustacea
Chapter 36
Diversity of Crustaceans, continued
Terrestrial Crustaceans
Sow bugs and pill bugs are terrestrial isopods.
They lack adaptations for conserving water and live only in moist environments.
They generally feed on decaying vegetation.
Pill bugs roll into a ball when disturbed or threatened.

22. Section 2 Subphylum Crustacea
Chapter 36
The Crayfish
The crayfish is an abundant freshwater crustacean that is structurally similar to lobsters, which are marine crustaceans.
Crayfish, lobsters, crabs, and shrimp are decapods, or members of the order Decapoda. Decapoda means “10 feet.”
Decapods have five pairs of legs that are used for locomotion.

23. The Crayfish, continued
Section 2 Subphylum Crustacea
Chapter 36
The Crayfish, continued
External Structure
The crayfish’s body is divided into
the cephalothorax, which is covered by the carapace and is divided into
the head, which has five segments
the thorax, which has eight segments
the abdomen, which is is divided into six segments

24. The Crayfish, continued
Section 2 Subphylum Crustacea
Chapter 36
The Crayfish, continued
External Structure, continued
A pair of appendages is attached to each segment of the crayfish. Several pairs have specialized functions.
These appendages include:
Antennae
Antennules
Mandibles
Maxillae
Maxillipeds
Chelipeds
Walking legs
Swimmerets

25. External Anatomy of a Crayfish
Section 2 Subphylum Crustacea
Chapter 36
External Anatomy of a Crayfish

26. The Crayfish, continued
Section 2 Subphylum Crustacea
Chapter 36
The Crayfish, continued
Digestion
Crayfish have a digestive gland that is near the stomach and that secretes enzymes for digestion.
Respiration
Walking circulates water across the gills.
Circulation
The circulatory system is open.

27. The Crayfish, continued
Section 2 Subphylum Crustacea
Chapter 36
The Crayfish, continued
Excretion
Green glands assist in excretion of excess water that enters the body by osmosis.
Neural Control
The nervous system of the crayfish is typical of arthropods and is similar to that of annelids.
Sensory Organs
Crayfish sense vibrations and chemicals in the water with thousands of small sensory hairs.
Their compound eyes are set on two stalks.

28. Internal Anatomy of a Crayfish
Section 2 Subphylum Crustacea
Chapter 36
Internal Anatomy of a Crayfish

29. Chapter 36 Anatomy of a Crayfish Section 2 Subphylum Crustacea
Click below to watch the Visual Concept.
Visual Concept

30. Characteristics of Crustaceans
Section 2 Subphylum Crustacea
Chapter 36
Characteristics of Crustaceans
Click below to watch the Visual Concept.
Visual Concept

31. Section 3 Subphyla Chelicerata and Myriapoda
Chapter 36
Objectives
List the characteristics of arachnids, as represented by a spider.
Explain the adaptations that spiders have for a predatory life on land.
Identify the unique characteristics of scorpions, mites, and ticks.
Compare the characteristics of millipedes and centipedes.

32. Subphylum Chelicerata
Section 3 Subphyla Chelicerata and Myriapoda
Chapter 36
Subphylum Chelicerata
The subphylum Chelicerata, the chelicerates, includes spiders, scorpions, mites, sea spiders, and horseshoe crabs.
Chelicerates lack antennae and typically have six pairs of appendages.
The first pair of appendages, the chelicerae, are modified into pincers or fangs.

33. Subphylum Chelicerata, continued
Section 3 Subphyla Chelicerata and Myriapoda
Chapter 36
Subphylum Chelicerata, continued
Class Arachnida
Class Arachnida, the arachnids, includes spiders, scorpions, mites, and ticks.
The arachnid’s body is divided into:
a cephalothorax that usually bears six pairs of jointed appendages:
one pair of chelicerae
one pair of pedipalps
four pairs of walking legs
an abdomen

34. Subphylum Chelicerata, continued
Section 3 Subphyla Chelicerata and Myriapoda
Chapter 36
Subphylum Chelicerata, continued
Anatomy of a Spider
Spiders have eight simple eyes and chelicerae that are modified as fangs.
Spiders produce silk threads using spinnerets.
Spiders respire through spiracles that connect to book lungs or tracheae.
Malpighian tubules function to excrete wastes while conserving water.

35. Anatomy of a Brown Recluse Spider
Section 3 Subphyla Chelicerata and Myriapoda
Chapter 36
Anatomy of a Brown Recluse Spider

36. Subphylum Chelicerata, continued
Section 3 Subphyla Chelicerata and Myriapoda
Chapter 36
Subphylum Chelicerata, continued
Life of a Spider
Spiders feed on insects and other small animals. Many species are adapted to capture certain prey.
Spiders rarely harm humans, but two species in the United States are dangerous:
the black widow
the brown recluse
A male spider is usually smaller than the female.
Females lay eggs in a silken case.

37. Feeding Habits of Spiders
Section 3 Subphyla Chelicerata and Myriapoda
Chapter 36
Feeding Habits of Spiders
Click below to watch the Visual Concept.
Visual Concept

38. Subphylum Chelicerata, continued
Section 3 Subphyla Chelicerata and Myriapoda
Chapter 36
Subphylum Chelicerata, continued
Scorpions
Scorpions have large, pincerlike pedipalps and a stinger on the last segment of the abdomen.
Mites and Ticks
Mites and ticks have a completely fused cephalothorax and abdomen.
Many species are parasitic, and some spread diseases that affect humans.

39. Chapter 36 Subphylum Myriapoda
Section 3 Subphyla Chelicerata and Myriapoda
Chapter 36
Subphylum Myriapoda
Members of the subphylum Myriapoda have antennae, mandibles, and unbranched appendages.
Class Diplopoda
Millipedes have rounded bodies and two pairs of jointed legs on each body segment except the last two segments.
Class Chilopoda
Centipedes have flattened bodies and one pair of jointed legs on each body segment except the first segment and the last two segments.

40. Characteristics of Arachnids
Section 3 Subphyla Chelicerata and Myriapoda
Chapter 36
Characteristics of Arachnids
Click below to watch the Visual Concept.
Visual Concept

41. Chapter 36 Types of Arachnids
Section 3 Subphyla Chelicerata and Myriapoda
Chapter 36
Types of Arachnids
Click below to watch the Visual Concept.
Visual Concept