Week 9 Flashcards
General attributes of Annelida
segmented” worms
Most marine
Body metameric
Paired epidermal setae
Closed circulatory system
Ventral nerve cord with dorsal suprapharyngeal ganglia
Protonephridia or metanephridia
What are setae
Hairlike, bristle structures that are associated with the body wall in annelids
Differentiate between metamerism and tagmatization
metamerism: segmented body
tagmatization: specialization of the segments
What is the peritoneum in the annelid body
- Thin sheet of cells lining the body cavity
- Shiny smooth
- A few cells thick
What are parapodia
in annelids, lateral extensions of the body wall
- Setae are the bristle like structures on them
can be used to walk by contracting longitudinal muscles
What is the prostomium in annelids
- Dorsal extension on most anterior part, kind of makes a mouth
- Contains structures
○ Sensory - eyes
○ Antennae - chemosensory
○ Palps - feeding structure
- Contains structures
Describe the circulatory system of annelids
Closed circulatory system
Dorsal blood vessel (above gut)
- Flows back to front
Ventral blood vessel
- Flows front to back
Parapod: have setae that break into capillary beds
Because ammonia is water soluble, marine annelids
can simply diffuse the nitrogenous waste through their body walls
How do terrestrial annelids excrete ammonia
as urea
Features common to Ecdysozoans
Ecdysis: They undergo periodic shedding of their outer covering.
Cuticle: They have a protective external cuticle.
Segmented body: Many possess a segmented body plan.
Bilateral symmetry: Their bodies are bilaterally symmetrical.
Nervous system: They have a centralized nervous system.
Complete digestive system: Most have a complete digestive tract.
Excretory organs: They possess specialized organs for waste removal.
Reproductive strategies: They display diverse reproductive methods.
Features of nematodes (round worms)
unsegmented, pseudocoelomate
layered cuticle
lack cilia typically
muscles run longitudinally to maintain its circular shape
dioecious
renette cells in excretory system
renette cells
glandular or tubular cells that absorb excess salts and move them to the excretory pore
define eutely
strict determined number of cells in its body
4 key features that lead to evolutionary success of arthropods
exoskeleton
segmentation and appendages
molting and growth
diverse reproductive strategies
Describe the process of ecdysis
1st
Hypodermis secretes enzymes that degrades the upper layers of the exoskeleton - underlying epithelium becomes separated
2nd
Secrete new material to be the base of the new exoskeleton
3rd
Old exoskeleton breaks up or animal crawls out
New exoskeleton takes a while to harden up - animal is quite soft and vulnerable to predation
