Major Divisions of Life

1
Homology Serial Homology Analogy
2 individuals structures have same developmental origin and same or different functions - 2 structures on 1 individual - 2 individuals - structures have different developmental origins but same function
quill hair bat wing hand cheliped swimmeret bird wing insect wing
2
analogy
homology
serial homology
3
How do the Arthropods fit in?
Arthropoda
Rotifera
Annelida
Nematoda
Platyhelminthes
Nemertea
Cnidaria
Porifera
unknown common ancestor
4
Phylum Arthropoda

• joint-footed animals

5
Fossil Record
A very ancient group with a 500 million year
fossil record
These fossilized tracks may push the date of land
arthropods back into the Cambrian
540 million years old
Devonian period
6
Fossil Record
These fossilized tracks may push the date of land
arthropods back into the Cambrian
Millions of years ago
today
0
65 end of dinosaurs
first dinosaurs, mammals, birds
213
First reptiles First amphibians
360
First land plants
First fishes
505
First Arthropods
Cambrian
590
First invertebrates
700
4,600
7
Phylum Arthropoda

• the largest phylum
• comprises 80 of all known animals

all other phyla
Arthropoda
8
Arthropoda Characteristics
Triploblastic
Organ level of organization
Bilateral Symmetry
Cephalization
Eucoelomate
Protostome
9
What characteristics have enabled Arthropods to
achieve such great diversity and abundance?
10
Arthropoda Characteristics
Exoskeleton

• hardened external cuticle secreted by the
  epidermis
• composed of chitin has internal
  ridges/projections called apodemes to which
  muscles attach
• benefits protection without loss of mobility
• limits growth? must be molted
• limits ultimate body size because of weight

11
Ecdysis (molting)
epicuticle
under hormonal control
exocuticle
endocuticle

• molting fluid dissolves old endocuticle
• new exocuticle is secreted

• new endocuticle forms under exocuticle
• exocuticle hardens

• new exocuticle is formed under the old one

• old exocuticle ruptures
• ecdysis! ? the animal
• backs out of old exoskeleton

12
Arthropoda Characteristics
Tagmatization and jointed appendages

• the fusion of segments into blocks called
  tagmata (singtagma) that are specialized for
  certain functions
• usually each tagma has a pair of jointed
  appendages
• appendages may be highly modified with tagmata
  being specialized for certain functions (e.g.
  feeding, moving, sensory)
• appendages are essentially hollow levers that
  are moved by well-developed striated muscles
  (flexors and extensors) and are capable of fast,
  powerful movement

13
Arthropoda Characteristics
Respiratory System

• on land most have a respiratory system that
  consists of tubes that deliver air directly to
  tissues and cells
• in water most have gills
• these systems allow for a higher metabolic rate
  and level of activity

14
Arthropoda Characteristics
Sensory System

• similar to Annelida
• (ventral nerve cord, cerebral ganglia/brain)
• possess a variety of sensory organs
• (e.g. simple and compound eyes, antennae,
  chemoreceptors, sensory hairs)

15
Arthropoda Characteristics
Complex Behavior

• have complex innate behaviors and some are
  capable of learning
• some even show communication and cooperation!

Spiny lobster cooperative behavior
Spiny lobster migration behavior
Dr. Herrnkind http//bio.fsu.edu/herrnlab/
16
Arthropoda Characteristics
Metamorphosis

• most have a larval stage that differs
  morphologically and behaviorally from the adult
• reduces competition between larvae and adults by
  allowing them to occupy different ecological
  niches

17
Arthropoda Characteristics

• no external cilia/flagella

Digestive System

• complete with regional specialization

Circulatory System

• open circulatory system consisting of a hemocoel
  (main body-cavity) filled with hemolymph (blood)

18
Arthropoda Characteristics
Excretion

• usually glands, some classes have specialized
  excretory systems

Reproduction

• usually sexual and dioecious
• usually internal fertilization

19
Phylum Arthropoda
(Arthropoda II)
Subphylum Trilobita
Subphylum Chelicerata
Subphylum Crustacea
Subphylum Uniramia
Class Branchiopoda Class Malacostraca Class
Copepoda Class Ostracoda Class Cirripedia
Class Merostomata Class Pycnogonida Class
Arachnida
Class Chilopoda Class Diplopoda Class Insecta
In your textbook, these are listed as
subclasses within the class Maxillopoda. But
follow what is here and in lab.
20
Subphylum Trilobita (Trilobitmorpha)

• all are extinct
• the most diverse of the extinct arthropod groups
  (5000 genera)

21
Subphylum Chelicerata

• no antennae
• 6 pairs of appendages
• 1st pair pincer, fang-like chelicerae
• 2nd pair pedipalps
• 3rd 6th pair walking legs
• body divided into 2 tagmata

opisthosoma consists of the abdomen
prosoma consists of the head and all the legs
22
Subphylum ChelicerataClass MerostomataHorseshoe
crabs have been essentially unchanged for 250
million years
23
Class Merostomata
opisthosoma prosoma
telson
carapace
compound eye
chelicerae
book gills
walking legs
24
Class Merostomata
25
Subphylum ChelicerataClass Arachnida
26
Class Arachnida
spiders, scorpions, ticks, mites, chiggers,
daddy longlegs

• They usually have several adaptations for life on
  land
• book lungs or tracheal system or both
• waxy cuticle

pedipalps
27
Class Arachnida

• arachnids as parasites
• chiggers (mites) and ticks

28
Class Arachnida

• arachnids as disease vectors
• Lyme disease is caused by infection with a
  bacteria that is transmitted by tick bites

Borellia
Deer tick
29
Subphylum ChelicerataClass Pycnogonida

• sea spiders
• 1000 marine species
• males carry the eggs

30
Subphylum Crustacea

• most are marine, some terrestrial and freshwater
• head has 2 pairs of antennae
• appendages are primitively biramous
• (have 2 major branches)
• body divided into 2 tagmata

cephalothorax consists of the head and the
thorax
abdomen
31
Subphylum Crustacea

• have mandibles, 2 pairs of maxillae, and 1 pair
  of legs per segment
• cephalothorax
• 2 pairs of antennae
• mandibles
• 1st and 2nd maxillae
• 3 pairs of maxillipeds
• 5 pairs of walking legs
• abdomen
• usually has 6 segments
• 1-5 have pairs of swimmerets
• last segment has a pair of uropods
• and a telson

32
Subphylum CrustaceaClass Branchiopoda

• sea monkeys and water fleas
• marine and freshwater
• important zooplankton

33
Subphylum CrustaceaClass Ostracoda

• have a bivalved carapace
• marine and freshwater
• reduced number of appendages
• bioluminescence

34
Subphylum CrustaceaClass Copepoda

• mainly marine, some freshwater and terrestrial
  (e.g. mosses)
• usually the most abundant animal in the plankton
• median eye

35
Subphylum CrustaceaClass Cirripedia

• acorn barnacles and gooseneck barnacles
• marine and sessile as adults
• feed with modified
• appendages called cirri

36
Class Cirripedia

• modified body form

cirri
penis
mouth
anus
Peduncle (absent in stalkless barnacles)
ovary
Adhesive gland
37
Class Cirripedia

• often form dense mats
• hermaphroditic with long extendable penis to
  reach neighbors

38
Subphylum CrustaceaClass Malacostraca

• largest class of Crustacea
• marine, freshwater, terrestrial
• shows great diversity

39
Class Malacostraca
very small to very large
40
Class Malacostraca
Many have complex behaviors
Finding a home
Attracting a mate
Etc
Brooding eggs
41
Subphylum CrustaceaParasitism
Fish louse
Parasitic isopods
Parasitic barnacles in the tissue, castrate crab
host, produce large egg-sac which the host then
broods as if it were its own
42
Subphylum Crustacea Commensalisms
Barnacles on whales
Pea crabs on a heart urchins sand dollars
Pea crabs in mussels
43
Subphylum CrustaceaMutualisms
44
Subphylum CrustaceaMutualisms

• e.g. cleaning shrimp

45
How do the Arthropods fit in?
Crustacea
Chelicerata
Uniramia
Trilobita
Nematoda
exoskeleton
Rotifera
tagmatization
Annelida
Nemertea
Platyhelminthes
Cnidaria
Porifera
unknown common ancestor