Evolution of Animals 2 Flashcards
What percentage of species are invertebrates?
95% of all species
What describes an invertebrate?
Absence of a backbone/spine
What did chordates and vertebrates evolve from?
Deuterostome
What is a porifera? What are 4 characteristics of it?
They are sponges
- Diploblastic
- Radial Symmetry
- Sessile (immobile)
- No true tissues
What is a Ctenophora? What are three characteristics of them?
They are simpler jellyfish
- Diploblastic
- Radial Symmetry
- They have multiple layers of cells.
What are the Ctenophora cell layers?
- A sensory epidermis
- A networked nervous system
What is a Cnidaria? How are they different from Ctenophora?
They are jellyfish as well with sessile polyps and swimming medusas. They also have a hydrostatic skeleton?
When did tripoblasty and bilateral symmetry evolve?
670Mya
What class of animals are bilaterally symmetrical?
Bilateria
What are two homoplasy’s of bilateria?
Acoela and Platyhelminths lost their body cavities and don’t have a digestive tract.
What is the classification of animals that have exoskeletons and molt often?
Ecdysozoa
What is the periodic molting of ecdysozoa called?
Ecdysis
What neural structures are found in arthropods? What other two characteristics do they have?
There are ganglions present in arthropods, and they show a rigid exoskeleton made of protein and chitin that is segmented.
What are the two sub classifications of the subphylum protostomia?
Lophotrochozoan and ecdysozoa
What are the two developmental structures associated with protostomia? Lightly describe them.
Lophophores are a crown of ciliated tentacles around the mouth for feeding, and Trochophores are a specific larval stage that somewhat resembles a clam shell.
What are the three deuterostome families?
Hemichordata, Echinodermata, and Chordata
When did chordata appear?
530 Mya
How are chordata different from the rest of the classes?
They are the only vertebrates
What is an example of Echinodermata and what are their three characteristics?
Starfish, and they are bilaterally symmetrical, deuterostomes, and have a water circulatory system called an ambulatory system
What is the ambulatory system of an echindodermata responsible for?
Nutrition, respiration, excretion, and locomotion
What are the 5 characteristics of chordata?
- They have a notochord
- Muscles are attached to said notochord
- They have a dorsal nerve chord (ectoderm stage of development)
- They have pharyngeal slits
- They have a post anal tail with skeleton and muscle
What is the oldest subgroup of chordates?
Cephalochordates
What are two characteristics of cephalochordates?
- Feeding through filtration in the pharynx
- Lateral movement for locomotion
What is the most recent invertebrate notochordate?
Urochordates
What is pedomorphosis? What family is it associated with?
It is the retention of juvenile characteristics of ancestors in adulthood and is associated with urochordates
What is special about urochordate larvae?
They developed the ability to reproduce before metamorphosis
What split urochordates from the rest of the notochords?
The loss of 4 hox genes
What class of animals was formed with the duplication of notochord hox genes?
Vertebrates
What is the role of the spinal cord?
Muscle attachment and protection of nerve tube
How is the spinal cord formed?
The solidification of vertebrae