subphylum vertebrata or craniata
TRANSCRIPT
Comparative anatomy of chordate
Subphylum Vertebrata or
CraniataLect. 4
Assist. lec. Sawsan S. Hameed
Biology Department
Tishk international University
2021-2022
Objectives
- Understand the general characteristics of Vertebrata
- Differentiate between super classes of Vertebrata
- Understand the features of super classes of
Vertebrata
- Describe and classify different classes of Agnatha
- Understand the classes of Agnatha, characteristics,
their classification with examples of each
➢ Called craniata due to presence of cranium,
➢ The names of Vertebrata is due to the change of
notochord to vertebral column
➢ Basic features
➢ A complex brain encased by a cranium, which protects and
supports it.
➢ Advanced nervous and sensory structures.
➢ Have endoskeleton
➢ Males and females are separate
➢ Gill slits are few in number, when present
➢ Variety of feeding strategies: herbivores, carnivores,
omnivores, filter feeders, parasites.
Subphylum Vertebrata or Craniata
Features of vertebrate
➢ Variety of habitats including freshwater, salt water,
terrestrial.
➢ Specialized epidermal structures; scales, feathers, hair,
fur, spines.
➢ True kidneys.
➢ Efficient respiratory system of gills or lungs
➢ Body is bilaterally symmetrical and of three parts - head
trunk and post-anal tail.
➢ Divided into 2 superclass
➢ Agnatha (Jawless Vert.)
➢ Gnatha (Jaw Vert.)
Class Ostracodermi
fossil
Class Myxini
Hag fishesClass
Cephalospidomorphi
(Lampery)
Agnatha
jawless vert.Gnatha
jaw Vert.
Super class Super class
Superclass Agnathan (jawless)
vertebrates➢ lack jaws hence the name agnatha (without jaw)
➢ Vertebral spine is cartilaginous in nature • head with a cranium
that encases a brain
➢ Mouth is generally round/ circular
➢ No scales or exoskeleton.
➢ Divided into 3 classes
➢Class Ostracodermi (fossil)
➢Class Myxini Hag fishes
➢Class Cephalospidomorphi (Lampery)
Agnathan (jawless) vertebrates
Class I : Ostracodremi ("shell-skinned") (extinct)
The earliest known vertebrates appear in fossils records of jawless primitive fish-like animals
Important features
➢ Primitive vertebrates, small to medium sized
➢ Body were fish-like, usually flattened dorso-ventrally, with a huge head and gill region
➢ No pectoral and pelvic fins but had only median fins
Exapmles : Cephalaspis , Pteraspis
➢ The head was encased in a solid shield made of broad bony dermal plates.
➢ This has led to their names Ostrochoderms (armoured fishes) or (bony skin) (Gr., orstracon= shell, derma = skin).
➢ Most kinds had a pair of large lateral eyes and median pineal eye on top of head
Agnatha (jawless) vertebrates
Dorsal fin
Dermal plater
Cephalaspis Pteraspis
➢ This group include two classes; Myxini (hagfishes), and Cephalaspidomorphi (lampreys).
➢ Members of this group lack jaws, internal ossification, scales, and paired fins.
➢ Both groups share pore like gill openings and an eel-like body form.
➢ In other respects, however, the two groups are morphologically very different.
➢ Notochord persists in adults
Living Agnathans (Jawless Vertebrates)
lampreys
Characteristic
➢ elongated eel-like body, lack jaws, true teeth, paired fins and bones
➢ Notochord remain throughout the life
➢ Lack vertebrae, but considered vertebrates because they have cranium and cartilagenous endoskeleton.
➢ Have single nostril loads to olfactory sac.
➢ Eyes are vestigial and covered by skin
➢ Have gill pouches
➢ All the hagfish are belong to one order Myxiniforms
Scientific classification
Kingdom: Animalia
Phylum: Chordata
subphylum vertebrate
Superclass Agnatha
Class: Myxini
Order: Myxiniformes
Class 2; Myxini
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Myxini
Order: Myxiniformes
Genus: Eptatretus
Genus. Eptatretusis a large genus of hagfish. It has at
around 48 described species at
present
Species: Eptatretus
stoutii➢ Is a species of hagfish.
➢ A jawless fish, lives in the
mesopelagic, near the ocean
floor.
➢ Produce large amounts of slime
➢ Eaten in Korea and other Asian
countries, along with its eggs and
its slime
Eptatretus stoutii
Eptatretus
➢ Agnatha vertebrates, lack jaws,
➢ Notochord remain through the
life and have primitive vertebral
column
➢ Have cartilaginous cranium &endoskeleton
➢ single median nostril
➢ Parasitic form prey on fishes
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata (Craniata)
Superclass Agnatha
Class Cephalaspidomorphi
Order Petromyzontia
Examples: marine lamprey Petromyzon marinus ,
freshwater lampreys Lampetra fluviatilis and L. planeri.
Class 3; Cephalaspidomorphi
➢ Median fins include two dorsal fins and caudal fin
➢ Seven pairs of gill pouches open separately to the exterior via gill slits
➢ larval stage are free living nonparasitic, mouth with upper
and lower lips.
➢ The larva is called Ammocoeta larva after 3 years then become adult after change in morphology and anatomy
Class III: Cephalaspidomorphi
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum Vertebrata
Superclass: Agnatha
Class Cephalaspidomorphi
Order: Petromyzontia
Genus: Petromyzon
Species: P. marinus
The sea lamprey (Petromyzon marinus)
➢ Is a parasitic lamprey found on
the Atlantic coasts of Europe and North
America
➢ It is brown, gray, or black in color
➢ Can grow up to 90 cm (35.5 in) long.
➢ Prey on a wide variety of fish.
➢ The Secretions in the lamprey's mouth
prevent the victim's blood from clotting.
➢ Victims typically die from excessive
blood loss or infection.
Petromyzon marinus
River Lamprey (Lampetra
fluviatilis)
➢ known as the European river Lamprey
or Lampern, Jawless lamprey
➢ Found in coastal waters around almost
all of Europe.
➢ Feeds as ectoparasites on fish.
➢ Migrate upstream from the sea
to spawning grounds in autumn
& winter
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum Vertebrata
Superclass Agnatha
Class: Cephalaspidomorphi
Order: Petromyzontia
Genus: Lampetra
Species: L. fluviatilis
Lampetra fluviatilisscientific name Lampetra
fluviatilis
Petromyzon marinus L. planeri
Lampetra fluviatilis
Sea Lamprey
1-Terminal mouth with four pairs of
tentacles. Buccal funnel absent. 5 to 16
pairs of pharyngeal pouches. About 65
species.
Hagfishes
2- No paired appendages,
3- No dorsal fin (the caudal fin extends
anteriorly along the dorsal surface.
4- Dorsal nerve cord with differentiated
brain, no cerebellum.
5- No larval stage.
6- Marine
1. Suctorial mouth with keratinized teeth.
Seven pairs of pharyngeal pouches. 41
species.
Lampreys: (Petromyzontes)
2. No paired appendages,
3. One or two dorsal fins.
4. Dorsal nerve cord with differentiated
brain, small cerebellum present.
5. Long larval stage (ammocoete).
6. Freshwater and marine
Class Myxini Class Cephalospidomorphi
Larval stage of lamprey
1. Ammocoete, is the larval stage of lamprey.
2. Its resemble amphioxus in many way.
3. Ammocoete do have several characteristics lacking in amphioxus that are homologous to those of vertebrates; these include:
➢ Chambered heart, well-developed brain, special sense organs, and pituitary gland.
Ammocoete
Oral hoodPharyngeal bars
Pharyngeal gill slits
Eye
brainOptic vesicle
anus
Post anal tail
Dorsal nerve cord
notocord
Larvae of lamprey Ammocoete
Jawless
mouth
Vestigial eye
Caudal fin
No scale
Buccal funnel First dorsal fin
Second dorsal fin
(Myxini Form)
Cephalaspidomorphi
Living Jawless Vertebrate
➢ In this lab, study all of the slides, reserved samples and pictures.
Starting by;
➢ Lamprey whole specimen
➢ Identify some chordates characteristics in a lamprey
➢ Pharyngeal slits, tail
➢ Draw it with all the labelling
➢ Slide of Ammocoetes, region of pharynx, gills and tail
➢ Study the chordates characteristics using the slide of
Ammocoetes. Notice the following;
➢ Notochord
➢ nerve cord.
➢ Region of gills
➢ Postanal tail
➢ Based on your information from the previous lab, how to differentiate
between the Amphioxus and the Ammocoetes?
➢ Draw all the slides, and whole specimen. Label all the structures that
you identify.
Lab study: Agnatha
References
For further reading please see:
Charles K. Weichert (2017). Elements of chordate anatomy. 3rd edition.
The McGraw−Hill Companies, New york.
Comparative anatomy | Definition, Examples, & Facts |
Britannicahttps://www.britannica.com › science › comparative-anatomy
Kardong, Kenneth V. (2019). Vertebrates: comparative anatomy, function,
evolution (8th edition). New York.
De Iuliis, G., & Pulerà, D. (2019). The dissection of vertebrates. 3rd
edition. Academic press. Elsevier, London.
Kenneth, S. S. (2017). The unity of form and function. 8th edition. The
McGraw−Hill Companies,. New york.
Comparative Anatomy. wwww.health.zone/