Chordates Flashcards
What are the features of Echinoderms?
Loss of Pharyngeal slits. Radial symmetry as adults. Exclusively marine. Bilaterally symmetrical larvae. Calcified internal plates. No head in adults (oral and aboral surfaces). Tube feet allows locomotion and foraging.
What are the features of Hemichordates?
Worm like. Marine. Two major groups and 3 main body parts. Breathing a gas exchange by pumping water through pharyngeal slits.
What are the two major groups of hemichordates?
Acorn worms which live in burrows and sand. Pterobrachs which are smaller and some are colonial. They have 9 pairs of arms with behind collar used to capture prey.
Give the three main body parts and their function
Proboscis is mucus covered to capture prey. The collar and the trunk.
What are the features of the chordates?
Notochord, dorsal hollow nerve chord and post anal tail. The notochord is composed of large cells with thick fluid vacuole, it is rigid but flexible.
What do urochordates and cepholochordates have in common
The majority are sessile. They have a bag like body enclosed in a tunic. Water pumped in through incurrent siphon to mouth. Food particles are moved by ciliary action.
Describe the features of Cepholochordates
Found in sediment in shallow marine waters. An example is the lanclets. Filter prey from water suing pharyngeal baskets.
Describe the features of urochordates
There are three major groups which are all marine. Ascideans, Thaliaceans, Larvaceans Many form colonies and can be up to several meters long.
Describe the features of vertebrates
Vertebral column. Anterior skull. Large Brain. Ventral heart. Internal organs suspended in coelom.
Describe the features of hagfish
Lack a vertebral column. Weak circulation (3 small hearts). No jaws or stomach. Produce lots of slime when feeding on rotting flesh.
What are lampreys?
Class Hyperoartia . Most are either fresh water or migratory. Complete cranium and separate vertebrae. Adults are ectoparasitic on fish. The larvae filter feed.
How did jaws evolve?
From skeletal arches allowing greater foraging efficiency and diversity.q
Give the features of cartilaginous fish
Sharks, rays and skates, they have paired, medium and caudal fins. They have a cartilage skeleton and some are filter feeders but most are predators.
What are the features of ray finned fishes
They are a very diverse group. Like cartilaginous fish they have paired, medium and caudal fins. They have a calcified bony skeleton with light weight scales. Buoyancy control. Gills open into a single chamber. Complex behaviours.
Describe lobe-finned fishes
They have two pairs of muscular joined fins and a cartilage skeleton.
Where are lung fishes predominantly found?
Africa and Australia. they have lungs.
What are the different tetrapod’s
Amphibians which lose water rapidly and have three major groups: Caecillians, Anurans, Salamanders.
Reptiles e.g. turtles, lizards, snake and crocodilians.
Aves (birds) feathers allow them to fly.
Mammals which have sweat galnds, mammary glands, hair and a four chambered heart.
Why adapt to use plants as a food source?
They are abundant, unexploited and there was a lack of competition.
What were the problems for using plants?
The cellulose was difficult to chew through and could not be digested in the gut, unlike starch which is similar to glycogen.
How have Jaws and teeth adapted for chewing plants?
Dental occlusion. Bone become stronger. Complex cusp pattern of molars and premolars develops for carnivores and herbivores. Herbivores have more molars and premolars which have ridges to improve grinding (crescent shaped and elongated).
How are browsers and grazers teeth adapted?
Browsers have teeth have low crowns, finite growth. Grazers have high crowned teeth that are constantly growing
What is the difference between hindgut fermentation and foregut ruminants?
Hindgut fermentation: enlargement of caecum
Foregut ruminants: enlargement of foregut and additional mechanical breakdown
Describe the features of hindgut fermentation
Faster digestion. Cellulose not fully broken down. Suits high starch, low energy food. Used by very small and very large animals.
Give the definition for adaptive radiation
The rapid evolution from a common ancestor of several species that occupy different ecological niches’. For example Darwin’s finches from Dull coloured grassquit
