Module 1 - Intro Flashcards
What is the difference between vertebrates and invertebrates?
Vertebrates: animals with internal skeletons that have backbones aka their support structure exists within the organism and is called an endoskeleton
Invertebrates = 90% of animal species: animals that lack a backbone and instead have an external supportive structure called an exoskeleton
What are anthropods?
Invertebrates (have exoskeletons) and a defining feature of jointed appendages that form legs, antennae, mouthparts, and repro organs
What are the 6 unique characteristics of anthropods?
- exoskeletons
- jointed appendages
- bilateral symmetry (can be split only along a single plane)
- tagmata (segmented bodies
- ventral nerve cord
- dorsal blood vessel
What are the 3 important axes to know for bilateral symmetry?
- dorsal-ventral axis (top to bottom)
- anterior-posterior axis (front to back)
- lateral axis (one side to the other)
What are tagmata?
Fused regions of body segments of anthropods with specialized biological fxns
Where is the nerve cord located in an anthropod?
ventral side
- unlike vertebrates where the cord is located on the dorsal side of the body
What are the 3 tagmata of insects?
- Head
- Thorax
- Abdomen
How does blood circulate in anthropods?
- blood vessel known as the dorsal blood vessel
- open circulatory system in which blood is pooled within the body cavity’ tissues are essentially in direct contact with the blood
Simply put, what 2 things make up the exoskeleton?
- Cuticle
- Epidermis
What is the cuticle of the exoskeleton?
A non-living structure that is secreted by the underlying epidermis, and is made up primarily of CHOs in the form of CHITINS as well as proteins
What are the 3 major layers of the cuticle of the exoskeleton?
- epicuticle
- exocuticle
- endocuticle
What is the epicuticle and its fxn?
Outermost layer of the cuticle.
- waxy, thin, no chitin (made up of wax and cement)
- fxns as a barrier to prevent water loss and the entry of disease-causing pathogens
What is the exocuticle and its fxn?
Portion of cuticle of the exoskeleton that carries pigments and is often hardened for protection and support
What is the endocuticle and its fxn?
Innermost layer of the cuticle, it is much softer and more flexible.
What is the fxn of the exoskeleton as a whole?
Provides protection and support for the animal and acts as a framework to which muscles and organs can be anchored
What is tanning? What happens to exoskeletons as a result of tanning?
The hardening of the exocuticle. In insects, tanning involves the cross-linking of proteins within the chitin matrix of the exocuticle in a process known as SCLEROTIZATION (unique to insects)
Exoskeletons become more opaque and darker.
How have anthropods evolved to register sensations through its exoskeleton?
SENSILLIA which perceive and transmit stimuli across the exoskeleton
What is the biggest disadvantage of the exoskeleton of arthropods?
It restricts growth since it does not grow with the organism so arthropods need to MOULT
Why do arthropods need to moult?
Exoskeleton doesn’t grow with them. As they grow in size they need to moult in order to replace their old exoskeleton with a new one. This process is regulated by hormones.
What is apolysis?
The beginning of the moulting process; separation of the old cuticle from the underlying epidermis.
To allow the old cuticle to separate, the underlying epidermal cells replicate in response to the release of ecdysteroid moulting hormone.
What hormone regulates moulting? How?
Ecdysteroid Moulting Hormone
- synthesized and released into the insect’s system by the prothoracic glands
- it causes underlying epidermal cells to replicate in order for the old cuticle to separate
What does apolysis achieve?
Creates an open space btw the cuticular layers into which digestive fluid is secreted. This breaks down the inner endocuticle into metabolites reabsorbed by the epidermal cells to form new cuticle.
What is Ecdysis?
The process of an arthropod shedding its old exoskeleton after the new cuticle has been fully formed following apolysis
How do arthropods increase it body volume to increase the size of the new exoskeleton it has gained through moulting?
- contract muscles to increase fluid pressure
- swallow air or water to inflate gut and body
New cuticle is initially pale and soft until it undergoes tanning
When did the first arthropods appear?
during the Cambrian period
- fossils suggest arthropods were the first animals to colonise land
Why did arthropods have an advantage to be the first animals to colonise land?
- stiff exoskeleton gave protection from desiccation and support against gravity
- jointed appendages provided locomotion not dependant on water
Taxonomy
the branch of science that deals with classifying and naming organisms
- research the discovery, description, and identification of an organism