Bryozoa Flashcards
1
Q
Introduction
4 points
A
- Sessile colonies of zooids
- Essentially marine, though some freshwater species
- Global distribution
- Benthic (mostly), occur at all depths
2
Q
Classification
A
Kingdom: Metazoa
Phylum: Bryozoa
Class: Pylactolaemata
Stenolaemata
Gymnolaemata
3
Q
Key characteristics
5 points
A
- Bilaterally symmetrical
- Triploblastic, Trimeric (tripartite), Enterocoelic coelomates
Tissues, organs, Through, U-shaped gut, nervous system
but no circulatory system or respiratory pigments
- Gas exchange via lophophoral tentacles
Colonial - Sexual reproduction
- Asexual budding
4
Q
Body structure
4 points
A
- Trimeric (tripartite)
Episome (prosome), mesosome,
metasome
- Coelomic compartments
Protocoel,
mesocoel,
metacoel - Body wall comprised of zoecium, epidermis and peritoneum
- Zoecium; chitinous, gelatinous, or calcareous
5
Q
Zooid colony formation
2 points
A
- Bryozoans are colonial
Consist of physically and physiologically integrated zooids
- Zooid polymorphism
Autozooids and heterozooids
6
Q
Zooid colony formation - 3 types of colonies
A
- Stolonate
Uncommon
Chitinous zoecium
Autozooids arise from stolon
2.Fruticose & Foliose Common Slightly calcified Look like seaweed One layer thick, or two layers back-to-back
3. Encrusting Very common Calcareous 2D, one layer thick mat Frequently epiphytic, could be considered parasitic
7
Q
Locophore
4 points
A
- Located on the introvert
- Encircles the mouth
Hollow, ciliated tentacles - Protraction controlled by muscular elevation of coelemic hydrostatic pressure
- Retraction controlled by two retractor muscles
8
Q
Feeding 3 points
A
- Utilise lophophore
- Suspension feeders
- Accessory feeding mechanisms:
Absorption of organic molecules
Tentacular flicking
Full-retraction
9
Q
sexual reproduction
4 points
A
- Hermaphroditic colonies, dioecious or hermaphroditic individuals (some protandric)
- External (rare) and internal
fertilisation - Indirect or mixed development
- Egg brooding
10
Q
asexual reproduction
A
Budding
11
Q
Class Stenolaemata
5 points
A
- Cylindrical zooids, no prosome or muscular layers
- Heavily calcified
- Terminal circular orifice - closed after retraction of the lophophore by a membrane
- Circular lophophore, 30 tentacles
- Only limited functional polymorphism
12
Q
Class Gymnolaemata
5 points
A
- Cylindrical or squat zooids, no prosome or muscular layers
- Form variable - soft or calcified
- Small, circular lophophore, variable forms
- Display distinct functional polymorphism
- Two orders
Order Ctenostomata
Order Cheilostomatida
