Animal Diversity Flashcards
(25 cards)
How and why are Animal Classifications modified?
- Eukaryotes
- Heterotrophic (cannot photosynthesize/make their own food)
- Lack cell walls
- motile
- asexual/sexual reproduction
- derived from a choanoflagellate-like common ancestor
What are the embryonic germ layers and what does each become?
The embryonic germ layers are: endoderm, mesoderm and ectoderm.
Endoderm transforms into the cells that are found in internal organs.
Mesoderm transforms into the muscle cells and connective tissue.
Ectoderm transforms into the nervous system and an outer protective layer like the skin (epidermis).
What is the difference between blastula vs gastrula?
In the earliest stage of embryonic development, the zygote develops into a multicellular embryo by cleavage which produces a hollow cavity - the blastula.
When an area in the blastula folds inwards or invaginates (process of gastrulation) this creates the gastrula structure, which results in the embryo having three layers of cells.
What is the difference between determinate vs indeterminate cleavage?
Determinate cleavage is a spiral cleavage that occurs in Protostomes and arrests the cell’s development. While, indeterminate cleavage is radial and occurs in Deuterostomes (like us, humans!), making normal cells.
Why are choanoflagellates believed to be the closest living relatives of animals?
Because they have shown genetic similarities
What major developmental features differentiate protostome vs deuterostome?
Protostomes develop into a mouth while Deuterostomes initially develop into a mouth and the second pore develops into an anus.
Which two clades gained a mesoderm layer vs the one that lost a mesoderm layer?
Ctenophores and Bilateria gained a mesoderm from their ancestor but Porifera lost its germ layers.
Contrast acoelomate vs pseudocoelomate vs coelomate
Acoelomates are triploblastic animals that do not develop an internal body cavity.
Pseudocoelomates have a body cavity or coelom that is not completely lined by tissue derived from the mesoderm.
Coelomates possess a body cavity that is completely lined with mesoderm.
What are examples of an acoelomate?
Flatworms (Platyhelminthes), jellyfish (Cnidarians), sponges (Porifera), and Comb jellies (Ctenophores)
What are examples of a coelomate or Eucoelomate?
Arthropods (arachnids, insects and crustaceans)
Annelida (segmented worms)
Mollusca (snails, clams, squids)
Echinodermata (sea stars, sea urchins)
Bryozoans and Brachiopoda.
What are examples of a pseudocoelomate?
Rotifera (rotifers) and Nematoda (roundworms).
What is the difference between trochophore vs lophophore?
Trocophore refers to a larvae stage found in several Lophophotrochozoans, where the middle section has a band of cilia used for swimming (worms and mollusks).
Lophophore is a horse-shoe shaped crown of tentacles used for feeding (rotifers, bryozoan and brachiopoda).
How can we differentiate between molecular classification vs morphological classification?
Molecular classifications group animals by changes in genes while, morphological classifications organize animals by their symmetry.
Compare and contrast Ecdysozoa vs. Lophotrochozoa
Ecdysozoa contains arthropods and nematodes. These organisms secrete an exoskeleton by the process of ecdysis (the molting of old exoskeleton to form a new one as the animal grows).
Lophotrochozoa, the 2nd clade in Protostomia, is characterized by morphological traits such as lophophores and trochophore larva.
Why is the animal kingdom referred to as monophyletic?
It has only one common ancestor.
True or False, more complex animals always have a larger genome than simpler animals. Why or why not?
False, smaller animals like newts have genomes that are 10x larger than the human genome.
Differentiate between Ctenophores vs Porifera vs Cnidaria which are all on the left of the phylogenetic tree.
Ctenophores have three germ layers and Cnidarians which only have two, but both have radial symmetry while Porifera do not have any symmetry and have lost their germ layers.
Differentiate between the morphological features of Radiata vs Bilateria. Give examples of animals in these clades.
Radiata organisms have radial symmetry and are diploblastic.
Bilateria have bilateral symmetry (mirrored sides) and are triploblastic.
What are some special traits of mollusks?
Mollusks have:
- a reduced coelom
- cephalization is present (sensory structures on anterior side)
Differentiate between the traits of flatworms (Platyhelminths) vs earthworms (Annelida) vs rounds worms (Nematoda)
Flatworms (no coelom) and roundworms (pseudocoelom) are not segmented while earthworms (Annelids) are and have coeloms.
What are the special traits of arthropods?
Arthropods are segmented like nematodes (roundworms) which results in a large degree of specialization of body regions.
They also have a reduced coelom and an exoskeleton.
What are important differences between Invertebrate vs Vertebrate Chordates?
The invertebrate and vertebrate chordates are classified under Deuterostomia. The main difference is that invertebrates do not possess a backbone while vertebrates do. Vertebrates are descendants of invertebrates only with modified structures (lengthened neck, jaws, lungs, limbs) to inhabit the land and sea.
Differentiate between Urochordates vs Cephalochordates
Urochordates are more closely related to vertebrates (like us!) and have an elongated chorda in the head region.
Cephalochordates are more closely related to Echinoderms and their chorda is in the rear or anterior region of the body.
What are special traits of Echinoderms?
Echinoderms have bilaterally symmetrical larvae and secondary radial adults.
They have no cephalization; no segmentation.
