Deuterostomes Flashcards
Deuterostomes are _______ symmetrical.
bilaterally
Deuterostomes are triploblasts. What are the three layers of a triploblast.
ectoderm,
mesoderm,
endoderm
Coelomate animals or ________, also known as ____________ - “_____ ________”) have a ______ filled body cavity called a ________ with a complete lining called _________ derived from _________, one of the three primary tissue layers.
Coelomata, Eucocoelomates, true coelom, fluid, coelom, peritoneum, mesoderm
Skeletal elements, where present are _______ rather than _______.
internal,
external
True or false?
Some deuterostomes are segmented and these segments are more obvious that those found in protostomes.
False.
Name 4 defining developmental characters of deuterostomes.
- Blastopore forms anus.
- Enterocoelous development.
- Radial cleavage.
- Indeterminate development.
In deuterostomes, the ______ develops from the blastopore.
anus
What is deuterostomy?
Mouth develops from the 2nd opening.
Briefly describe enterocoelous development.
Coelom formed by out-pocketing of the embryonic gut, creating “enterocoelic pouches”
Briefly describe radial cleavage.
Cleavage of cells of the blastula occurs in a radial pattern
Briefly describe indeterminate development.
Fate of cells is not fixed until a late stage of morphogenesis.
Briefly SUMMARISE radial cleavage.
Cells parallel or perpendicular to animal-vegetal axis.
Cells lie beside and on top of each other.
Briefly SUMMARISE indeterminate development.
Cells separate after several divisions still develop into complete embryos. (Identical twins)
Indeterminate cleavage is typical in ___________. If these cells are separated from each other, what could happen?
Deuterostomes;
if the cells are separated, each has the potential to develop into an entire organism on its own.
Determinate cleavage is typical in _______. If these cells are separated, what would happen?
Protostomes;
If the cells are separated, they will die. Neither has the potential to develop into an organism on its own.
What are the three major deuterostome clades?
Echinoderms (Sea Lilies, Feather Stars, Brittle Stars, Sea Stars, Sand Dollars, Sea Urchins, Sea Biscuits, Sea Cucumbers);
Hemichordates (Acorn Worms);
Chordates (Subphylum Urochordata - Tunicates & Subphylum Cephalochordata - Lancelets)
What are the two major clades that are grouped together? What is the name of this formation?
Echinoderms & Hemichordates are grouped to form AMBULACRARIANS
What are xenoturbellids?
Small, wormlike animals that parasitize/feed on molluscs.
They have a simple body plan, no well-defined organ systems.
What are acoels?
a class of small and simple wormlike animals
_____ are among the smallest bilateran animals, with no gut, circulatory system, respiratory system, body system or excretory system.
Acoels.
What are the two sub-phyla in Chordata?
Urochordata;
Cephalochordata
Briefly describe invertebrate chordata. (3 points)
* 2 - 3000 invertebrate species (2 subphyla); Marine; Bilaterally symmetrical; Deuterostome; Segmented body; Triploblastic; Well-developed coelom; Radial, indeterminate cleavage; Indirect development (larval stages)
There are ____ invertebrate chordate hallmarks.
five
Key information about the invertebrate chordate hallmarks.
ALWAYS in embryonic stage;
May alter/disappear later in lifecycle;
All UNIQUE to chordates (except pharyngeal slits).
What are the five invertebrate chordate hallmarks? Briefly describe.
- Notochord - Flexible, rod-shaped structure, extending the length of the body. Axis for muscle attachment and allows body movements.
- Dorsal hollow nerve cord - Above the notochord, invertebrate chordates: dorsal to alimentary canal and a hollow tube. Other invertebrates: solid nerve cord ventral to alimentary canal.
- Pharyngeal slits - openings from pharyngeal cavity to outside. Invertebrate chordates: filter feeding apparatus - vertebrates - bony fish: develops into gill arches; terrestrial vertebrates: develops into jaw and inner ear.
- Post-anal tail - posterior elongation of body, extending beyond anus, tail contains skeletal elements and muscles for locomotion in aquatic species.
- Endostyle - new character: elongated ciliated groove on pharyngeal floor. Early chordates: invertebrate chordates and vertebrate lampreys: secretes mucus to trap food; advanced chordates, becomes thyroid gland.
__________, the lancelets, retain a chordate body plan throughout life.
Cephalochordates
___________, the tunicates, only retain a full chordate body plan in the larvae.
Urochordates
The __________ have around 25-28 species in a single class. The original name was Amphioxus but the name was replaced with ____________ spp. They display all five chordate hallmarks ______________ _____.
Cephalochordates;
Branchiostoma;
throughout life
Cephalochordata are ______ (around _____cm). Briefly describe their body.
Small; <10; Slender; Body laterally compressed; fish-like; translucent
Cephalochordates can be found ______ and are _____ creatures.
worldwide;
marine