Module 1 Flashcards
How much of all named species are insects
About 50 percent
Vertebrates
Have an internal skeleton and a spinal column to reach large body sizes
Invertebrates
No internal support structure
Support structure is outside the body
Exoskeleton
What animals are vertebrates
Fish
Birds
Amphibians
Reptiles
Mammals
All other animals are invertebrates
Arhtropods are
Organisms with jointed appendeges
Arhtropods make up what percentage of known organisms
60 percent
Arthropod body plan
Bilateral symmetry
Segmented body
Ventral nerve cord
Dorsal blood vessel
Exoskeleton
Bilateral symmetry
If an organisms can be split vertically evenly
Radial symmetry
Circular body plan
Dorsal ventral axis
Top to bottom
Anterior posterior axis
Front to back
Lateral axis
One side to another
Ventral nerve cordis exclusive to
Arthropods
Arthropod open circulatory system
Athropods don’t have a networ of blood vessles but rather a single dorsal blood with openings to criculate blood
Tissues are directly exposed to this
Exoskeleton
Made up of cuticle and epidermis
Cuticle is made up of
Chitin
Layers of cuticle
(Top to bottom)
Epicuticle
Exocuticle
Endocuticle
Epidermis
Layer beneath the cuticle that secretes it
Basement membrane
Seperates epidermis from body cavity
Epicuticle
Prevents water loss and prevents disease
Exoskeleton ridges
Internal ridges that act as sites for muscle attachment and provides support for the internal organs
Exoskeleton is both
Hard and fleixble
Exocuticle
Hardened through tanning and maybe mineralization and calcification
Tanning
Cross-linking of proteins- also known as scleritization
Endocutucle
Soft and fleixble layer
Exoskeleton constraints
Limits size of organism
Arthropod solution to constraint
Moulting- shedding exoskeleton for new one
Moulting step 1
Apolysis
Seperation of old cuticle from underlying epidermal cells
Apolysis is triggered by
Ecdysteroid moulting hormone from prothoracic glands
Moulting step 2
Digestive fluid breaks down endocuticle
Moulting step 3
New cuticle is secreted by epidermal cells
Moulting step 4
Ecdysis
Old cuticle is cast off
New cuticle after moulting is
Pale and soft
To increase hardness of cuticle atrhtopods
Contract its muscles to increase internal fluid pressure in its body
This inflates the gut to occupy more space
Cost of moulting
Very vulnerable to predation and desicration
First athropods came in the
Cambrien period
Most dominent atrhropod during cambrien
Trilobytes
Trilobyte features
Spiny exoskeleton for defense
Distinct body segmentation
Jointed legs
Trilobyte lived in
Water environments
Earliest land animals were
The arthropods in the celerian period
Arthropod traits that made them fit for land
Exoskeleton and jointed legs to provide protection from drying out and gravity and means of locomotion
More recent arthropod that evolved
Honeybees (34 million years ago)
Insect fossils at the U of A
Can be 56 million to 39 million years old
Trilobytes first evolved
520 million years ago
Trilobytes went extinct
250 million years ago
Lived 4 major extinction events
Phylogeny
Evolutionary history
Taxonomy
Classifying and naming organisms in a system
Taxonomic ranks
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
All animals belong to the kingdom
Anamillia