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
Cephalochordata was originally considered to resemble closely direct ancestors of vertebrates but now, are a ______ _____ __ ________.
side branch of Chordata
Cephalochordata are not ___________. They have a ____ ____ with tentacles around the mouth for ______-________. Most of the body contains a large ________, with ______ and lined with _______. They have _______, meaning they are ________. Fertilisation occurs _______ the body and so the larvae are ____ ________. They do not have a ______, a ________ ________, _________, the notochord is not replaced by a ________ _______.
Vertebrates; oral hood; filter-feeding; pharynx; slits; mucus; gonads; dioecious; outside; free swimming; brain; protective cranium; vertebrae; vertebral column.
Urochordata, also known as ________ or “____ ______”. There are around ______spp. Adults are _______ while larvae are ____ _____. They are _______ and ______. Adults display ___ of the five chordate hallmarks. What are they?
Tunicates; Sea squirs; 2000; sessile; free living; solitary; colonial; 2; Pharyngeal slits & Endostyle.
Acorn worms, otherwise known as ________ or ____ _______. They share some characters with the chordates. What are they?
They also share some characters with the echinoderms. What are they?
However, these creatures, lack some chordate features. What do they lack?
Hemichordata;
Half chordates;
Hollow dorsal nerve tube & Pharyngeal slits;
Tornaria larvae (with ciliated bands);
Notochord & post-anal tail (not locomotory)
Name at least 4 Hemichordata characteristics.
Deuterostome bilaterally symmetrical, triploblasts;
Radial and indeterminate cleavage;
Small marine group, bottom dwellers;
Soft bodied, worm-like OR short and compact with stalk for attachment;
Most sedentary or sessile;
Distribution cosmopolitan;
Three body regions: Proboscis; Collar; Trunk
What are the three body regions of hemichordates?
Proboscis;
Collar;
Trunk
What classes are in the Hemichordates? What do they mean?
Enteropneust; Gut-breathing.
Pterobranch; Feather-like
Briefly describe the class Enteropneust.
Gut-breathing; Around 70 species in 4 families; Variable size (20mm - 2.5m); Free-moving; vermiform; burrowing; ciliary tract; Most species form mucus-lined burrows in sandy/muddy sediment (shallow water); Many pairs of pharyngeal slits (up to 100)
Briefly describe the class Pterobranch.
Feather-like; 15-30 species in 3 families; Very small (1-12mm); Sessile; tubiculous; often colonial; lophophore; One paire of pharyngeal slits (some have none.)
What does it mean to be a lophophore?
a structure in certain small marine invertebrates, having the shape of a horseshoe and bearing ciliated tentacles around the mouth.
Some creatures in Pterobranch are solitary while others form colonies with individuals connected by stems. What is another word for these stems?
Stolons
Name the four main characteristics that define a Deuterostome.
Blastopore forms anus;
Enterocoelous development of body cavity;
Radial cleavage;
Indeterminate development
What are the main phyla within invertebrate deuterostomes?
Hemichordata (acorn worms);
Echinodermata;
Chordata
What are the main subphyla within invertebrate deuterostomes?
Chordata (phyla)
Subphyla = urochordata & cephalochordata
What characters define invertebrate chordates?
Notochord; dorsal hollow nerve cord; pharyngeal slits; post-anal tail; endostyle
What defines Hemichordata?
“half-chordate”;
Share some characters with Chordates;
Share some characters with Echinoderms;
But lack a notochord and a post-anal tail;
Typical taxa are the acorn worms (enteropneusta) & pterobranchs.
Name at least three characteristics of the phyla Hemichordata
- Deuterostome bilaterally symmetrical, triploblasts
- Radial and indeterminate cleavage
- Small marine group, bottom dwellers
- Soft-bodied, worm-like OR short and compact with stalk for attachment
- Most sedentary or sessile
- Distribution cosmopolitan
- Three body regions; Proboscis; Collar; Trunk
What are the two classes that come under the phyla hemichordata?
Enteropneust (gut-breathing)
Pterobranch (feather-like)
Briefly describe the class Enterpneust
- Around 70 species in 4 families
- Variable size (20mm - 2.5m)
- Free-moving, vermiform, burrowing, ciliary tract
- Most spp. form mucus-lined burrows in sandy/muddy sediment, shallow water
- Many pair pharyngeal slits (up to 100)
Briefly describe the class Pterobranch
- 15-30 species in 3 families
- Very small (1-12mm)
- Sessile, tubicolous, often colonial
- Lophophore
- One pair of pharyngeal slits (some have none)
What are the main characters which define Deuterostomes?
- Blastopore forms anus
- Enterocoelous development of body cavity
- Radial cleavage
- Indeterminate development
What are the main phyla and subphyla within invertebrate Deuterostomes?
- Phylum: Hemichordata (Acorn worms)
- Phylum: Echinodermata
- Phylum: Chordata
- Subphyla: Urochordata (Tunicates)
- Subphyla: Cephalochordata: Lancelets
What characters define invertebrate chordates?
- Notochord
- Dorsal hollow nerve cord
- Pharyngeal slits
- Post-anal tail
- Endostyle
What defines Hemichordata?
- “Half-chordate”
- Share some characters with chordates: e.g. hollow dorsal nerve tube and pharyngeal slits
- Share some characters with echinoderms: e.g. tornaria larvae (ciliated bands)
- But ALL lack the notochord & post-anal tail
- Typical taxa are the acorn worms (enteropneusta) & Pterobranchs
Name at least 3 species that come under the phyla Echinodermata
- Sea lilies
- Feather stars
- Brittle stars
- Sea stars
- Sand dollars
- Sea urchins
- Sea biscuits
- Sea cucumbers
Name at least 3 characteristics of members of echinodermata
- Typically deuterostome; blastopore becomes anus; radial cleavage; enterocoely
- Reproduce mostly sexually; generally dioecious; most species go through external fertilisation
- Some asexual reproduction; splitting (transverse fissions) pathogenesis
- Autotomy & regeneration of lost parts
- No specialised excretory organs in adults
- Decentralised nervous system
Echinoderm symmetry. Describe the symmetry of:
Sea star larvae
&
Adults
Sea star larvae: Bilateral symmetry
Adults: Radial symmetry - 5 rayed radial symmetry - Pentamerous
The endoskeleton beneath the epidermis is composed of small calcareous plates called _______
Ossicles
Skeletal plates connected by collagen which can be stiff or flexible “_______________”
Changes from liquid to solid;; stimulated by __________________.
Catch collagen
The nervous system
Briefly describe the Water Vascular System displayed in Echinodermata
- Set of canals & specialised tube feet, together with dermal ossicles
- Forms hydraulic system used for locomotion, feeding, waste transport and respiration
- Water enters through pore which leads down to stone canal - Madreporite
- Circulates through canals that lead down to tube feet - Ampulla
Explain a madreporite
Water enters through pore which leads down to stone canal
Explain ampulla
Tube feet to which water circulates through canals towards
In the tube feet of echinoderms, fluid is pumped into the foot by contraction of the _______.
___________ at junction of ampulla/radial canal. Tube foot retracts when ______________ in each tube foot contract.
A single echinoderm has more than _____ tube feet.
Apulla
One-way valve
Longitudinal muscles
2000
How many classes are in the phyla echinodermata?
6; Ophiuroidea; Asteroidea; Echinoidea; Crinoidea; Holothuroidea; Concentricycloidea
Name at least three characteristics of the class, Crinoidea
- 650 species
- Tube feet ONLY used in food collection, gas exchange and excretion
- Pinnules (side branches), columnals
Name at least three characteristics of the class, Echinoidea
- 950 species
- Spherical (regular) or secondarily flattened (irregular), free-living, lack of arms
- Grazing apparatus
- Appendages: spines (sharp & contain toxins for defence), pedicellaria
What is Aristotle’s Lantern? Briefly explain.
- Biting and rasping
- Composed of 50 skeletal elements; worked by 60 muscles
- 2 powerful blocks of muscle between pyramids close the jaws & provide strong biting action
Name at least three characteristics of the class, Asteroidea
- 1500 species
- Live in shallow and deep habitats
- Mostly predators, everts stomachs
- Macrophagous feeding
What are papulae?
- Non-calcified out-foldings of body wall
- Respiratory function (skin gills)
Briefly describe the class Asteroidea
- Among the largest sea stars, spines have neurotoxins
- Voracious predators of coral
Name at least three characteristics of the class ophiuroidea
- 2000 species
- Many mucociliary suspension feeders
- Large stomach, no intestine, no anus
- Long, slender arms, often with spines, fast moving
- Secretive predators, some bioluminescent
Name at least three characteristics of the class holothuroidea
- 1200 species, scavengers
- Usually soft-bodied, ossicles reduced
- Lack arms: secondary bilateral symmetry
- Respiratory trees (2 long many branched tubes); respiratory and excretion
- Unique defence; Some expel CUVIERIAN TUBULES (sticky/toxic structure)
- Or EVISCERATION (entire digestive system expelled)
Name at least three characteristics of the class concentricycloidea
- 2 species, medusa-like echinoderm
- Little known; 1st discovered in 1986 from deep water (1-2000m) from New Zealand
- Tiny, flat, armless disc-shaped bodies surrounded by a ring of marginal spines
- Apparently eat prokaryotes, which they digest outside their bodies and then absorb
- Phylogenetic position uncertain
Main characters which define echinoderms
- Bilateral symmetry as larvae and radial symmetry as adults
What are the evolutionary innovations of echinodermata?
- Water Vascular System for locomotions, feeding, waste transport and respiration
- Endoskeleton - internal calcified skeleton with catch collagen for unique mechanical support
What are the 5 main groups within the phyla echinodermata
- Asteroidea
- Echinoidea
- Ophiuroidea
- Crinoidea
- Holothuroidea
What is important about the 5 main groups within the phyla echinodermata?
- Regeneration
- Defence (spines, pedicellariae, evisceration)
- Grazing apparatus
- Microphagous feeding
