Lecture 13 - Agnatha Flashcards
Explain Deuterostome coelomates
- Bilateral symmetry
- Three germ layers
- Organ level organization
- Tube-within-tube body plan
Explain Phylum: Echinodermata
- All marine.
- Share an evolutionary branch with chordates
- Include some of the most colorful and amazing sea animals
- Radial symmetry as adults, but the larvae are bilateral symmetrical and free swimming.
- Symmetry is penta-radiate; Internal Ca-rich plates-endoskeleton
- Spiny skin which is connected to internal skeletal plates
- Breathe through skin gills-extensions of the coelom-for respiration and waste removal
- Possess a water vascular system
What does the water vascular system of Phylum: Echinodermata
Assists with circulation, respiration, excretion and movement.
How do Phylum: Echinodermata share an evolutionary branch with chordates
Because of bilateral symmetry and deuterostome coelom
Explain Class: Crinoidea
- Oldest class
- Includes featherstars & sea lilies
- Feathery arms are used in filter feeding
- Free swimming, and move by tube feet
Explain Class: Ophiuroidea
- AKA brittle stars
- Have flat circular bodies with 5 arms
- Arms have small plates & projections
- Browse on ocean floor or filter feed
- At the base of each arm there is one larger scale (= radial shield)
eg) 1. Amphiura capensis (equal-tailed brittlestar)
- Ophioderma wahlbergi (serpent-skinned brittlestar)
Explain Class: Holothuroidea
- Common name is Sea cucumbers
- Resemble cucumbers with tentacles at oral end
- Body consists of an elongated tube form which is divided into 5 parts.
- No arms, spines absent.
- Browse on ocean bottom
Example: Roweia frauenfeldii (horseshoe sea cucumber)
Explain Class: Echinoidea
- Commonly known as Sea urchins
- They have spiny calcareous bodies
- Spines are for locomotion, burrowing & defence
- Globular (urchins) or disc-shaped (sand dollars)
- Penta-radiate symmetry
- They possess tube feet.
- Many feed on sea weeds
- Parechinus angulosus (Cape urchin), Echinodiscus bisperforatus (Pansy shell)
Explain Class: Asteroidea
- Commonly known as sea stars, they are predators
- Body consist of five arms.
- Body = covered with spines for protection
- Pedicellaria
- Skin gills are small projections near the base of the spines
- Ventral tube feet aid in locomotion and feeding
- Well-developed coelom in arms
- Sexes separate ( Sexual and asexual reproduction )
- Water vascular system – locomotion, excretion, respiration and circulation
- Composed of canals connecting numerous tube feet. - Predators on Bivalves, and other echinoderms
Examples: Marthasterias glacialis, Patiriella exigua (dwarf cushion star), Henricia ornata, Patiria granifera (red starfish)
Explain Pedicellaria of Class: Asteroidea
Defensive organ that looks like a tiny pincer, present to keep the body free from organisms settling on it.
What are the subphylum of Phylum: Chordata
- Subphylum: Urochordata
- Subphylum: Cephalochordata
- Subphylum: Vertebrata
Explain Phylum: Chordata characteristics
- Presence of a notochord
- Presence of dorsal tubular nerve chord
- Pharyngeal pouches
- Post-anal tail whether in adult or embryo is present in chordates
Explain the Presence of a notochord
- Below the nerve cord
- In vertebrates the embryonic notochord is replaced by the vertebral column.
Explain the Presence of dorsal tubular nerve chord
- In vertebrates the nerve cord is the spinal cord
- In vertebrates it is protected by the vertebral column
Explain the Pharyngeal pouches
- Present during the life history. In the invertebrate chordates, fish and amphibian larvae, the pouches become gills
- In Vertebrates they become modified.
Explain Subphylum: Cephalochordata
- They are known as lancelets (means surgical knives)
- The notochord stretches from head to tail (cephalochordate)
- All 4 chordate characteristics retained as adults
- Segmentation visible. The muscles are segmentally arranged
- They are all marine and live in sand and muddy coastal waters, filter feeders
Example: Branchiostoma (= Amphioxus)
Explain Subphylum: Urochordata
- Known as tunicates- They include sea squirts, red bait
- Larvae exhibit all 4 chordate characteristics
- Bilateral symmetrical larvae
- Adults retain gill slits
- Sea squirts and red bait are marine species
- The body is protected by a thick-walled tunic
- They are sessile
- They use an excurrent siphon to siphon water and squirt water
Examples: Pyura stolonifera (red bait), Ciona intestinalis
Explain Subphylum: Vertebrata
- Animals with a living endoskeleton with vertebral column
- They have a closed circulatory system-a heart and vascular system
- Paired appendages
- Efficient respiratory & excretory systems
- High degree cephalisation
- Segmentation present – presence of a vertebral column
- Complex brain; nervous system well developed
Explain vertebrata in more detail
- Digestive system complete and well developed.
- Kidneys –assists with water retention and excretion
- Sexes separate and sexual reproduction takes place
- Amnion(membranous sac which surrounds and protects the embryo) present to enable development on land
- Some lay eggs; others have placenta
What are the super classes of Subphylum: Vertebrata
- Super class: Agnatha
(Those jawless “monsters”) - Super class Gnathostomata
(animals with jaws)
What are the classes of Super class: Agnatha
- Class: Ostracodermi
- Class: Cephalaspidomorphi
- Class: Myxinii
Explain Superclass: Agnatha
- Jaws were absent)
- Have slender eel-like bodies
- Have a fibrous or cartilaginous skeleton
- Possess seven or more pairs of external gills
- Notochord present throughout adult life
- Scales and paired appendages (fins) absent-
- Have smooth bodies
- Early species had heavy bony scales and plates in their skin, not present in living species.
- In most cases skeleton is cartilaginous.
embryonic notochord persists in the adult. - 7 or more paired gill pouches are present.
Explain Class: Ostracodermi
- Extinct taxon of Cambrium to Devonian periods
- They were jawless, finless, FILTER FEEDERS.
- Bony skeletal elements were present in some forms
- They had large defensive head shields
Explain Class: Cephalaspidomorphi
- AKA fish with head shield present [Gk. Cephalo, head, spido, shield, morph, form]
- Known as lampreys
- Circular mouth with teeth on an oral disc.
- They have no jaws, many teeth enclosed in a sucker-like mouth.
- They are capable of latching on and boring into the sides of their hosts to hitch a ride and grab a free meal.
- Oviparous-produce young by laying eggs; larva (is called ammocoetes live on detritus and microorganisms)
- Seven pairs gills, pineal eye(a light receptor), two pairs semicircular canals in the inner ear.
Examples: Petromyzon (marine), Lampreta (freshwater)
Explain Class: Myxinii
- Hagfish are the only animals with a cranium but no spinal column.
- Have a cartilaginous notochord—a skeletal rod that most vertebrates lose in utero—that gives them amazing flexibility
- Marine burrowers, with 5-7 pairs of gills, and NO EYES
- Teeth on tongue; tentacles around mouth
- They have many slime glands
- Heart: “4-hearts
- Hermaphroditic; no larvae
- They live in dead bodies.
Example: Myxine
