Lesson 1 Flashcards
Animals have 4 features
- Multicellular
- heterotrophic
-eukaryotes - have tissue that develop from embryonic layers
Cleavage
- the zygote undergoes a succession of mitotic cell divisions (without cell growth between the divisions)
- leads to the formation of the blastula
Blastula
-after cleavage- it is a hollow mass structure in the form of a ball
-gastrulation comes after
Gastrulation
- One end of the embryo folds inwards, expands, and eventually fills the blastocoel, producing layers of embryonic tissues; the ectoderm (outer layer), and the endoderm (inner layer)
- Layers of embryonic tissues that will develop into adult body parts are produced
- Ends with a gastrula
larva
-A sexually immature form of an animal that is morphologically distinct from the adult
-usually eats different food
- may have a different habitat than the adult, as in the case of the aquatic larva of a mosquito dragonfly
Metamorphosis
Animal larvae eventually undergo metamorphosis, a developmental transformation that turns the animal into a juvenile that resembles an adult but is not yet sexually mature.
What are the 6 stages of early embryonic development in animals?
- Cleavage … (eight cell stage)
- Blastula
- Gastrulation
- Gastrula
- Larva
- Metamorphosis
What is the cavity inside the blastula called?
blastocoel
Cross section of the gastrula
- the pouch formed by gastrulation, called the archenteron, opens to the outside via the blastospore
- the endoderm of the archenteron develops into the tissue lining the animal’s digestive tract
Which animals do NOT have Hox genes?
sponges
Animal development is controlled by a similar set of ____across a broad range of taxa.
hox genes
Hox genes
regulate the formation of the posterior-anterior (front-to-back) axis, as well as other aspects of development
How many extant species of animals are identified?
1.3 million
Ediacaran biota (neoproterozoic era 1B- 542M years ago)
an early group of soft-bodied multicellular eukaryotes (dates from 560 million years ago)
earliest known macroscopic animals
Cambrian explosion
another wave of animal diversification around 535-525 million years ago, during Cambrian period of the paleozoic era
most of the fossils from the Cambrian explosion are ___.
bilaterians
bilaterians
an enormous clade whose members have a two-sided or bilaterally symmetric form and a complete digestive tract (mouth and anus).
Why is the Burgess Shale important?
This site preserved fossils from the Cambrian period.
body plan
A particular set of morphological and developmental traits integrated into a functional whole-the living animal
radial symmetry
ex: sea anemone (phylum Cnidaria)
does not have a left or right side. Any imaginary slice through the central axis divides the animal into mirror images.
Bilateral symmetry (they have brains)
ex: lobster (phylum Arthropoda)
has a left and right side. Only one imaginary cut divides the animal into mirror-image halves.
diploblastic animals- which tissues do they have (2)? And which phyla (1)?
Cnidarians and a few other animal groups that only have the ectoderm and endoderm
Triploblastic
Having a mesoderm. Most bilaterally symmetrical animals are triploblastic. ex vertebrates, arthropods, and flatworms.
mesoderm
forms the muscles and most other organs between the digestive tract and the outer covering of the animal
body cavities définition and function?
Fluid-filled spaces located between different tissue layers.
Functions include:
1structural support for the body,
2.formation of an internal transport system to supply nutrients,
3.allow efficient gas exchange,
4.and remove waste
What are the body cavities of triploblastic animals? (3)
- Coelom
- Hemocoel… fluid = hemolymph
- Compact
What does the archenteron become?
the gut
What are the 3 characteristics that define animals?
- Nutrition
- Cell structure and specialization
- Reproduction and development
Animal’s nutritional mode?
Heterotrophs; ingest organic molecules and digestive enzymes produced within specialized cavities (mouth, stomach, and small intestine), digest them down to bits small enough to be absorbed across epithelial cells
- they CANNOT make their own organic molecules
- they obtain their molecules from the food that they ingest and digest in their bodies
which tissues are defining characteristics of animals? (2)
- Nervous tissue
- Muscle tissue
What are the cell structure and specialization of animals? (4)
- eukaryotes
- have no cell walls
- bodies are held together by structural proteins such as collagen!
- nervous tissue and muscle tissue are defining characteristics of animals
What is an animal? (4)
- how they acquire and assimilate nutrients
- the presence of molecules and tissues that are exclusive to animals
- their mode of sexual reproduction
- the presence of hox genes that determine their embryonic development
are plants photoautotrophs?
are they unicellular or multicellular?
- yes, using the energy from the sun, plants convert carbon dioxide into molecules of glucose.
- multicellular
are fungi heterotrophs or autotrophs? are they mostly unicellular or multicellular?
- heterotrophs; secreting digestive enzymes directly into their environment. These digestive enzymes break down complex organic molecules and digest them down to soluble products, small enough to e absorbed across the hyphal cells.
- mostly multicellular
a single hox gene set contains…
13 genes
how many sets of hox genes to vertebrates have vs invertebrates?
vertebrates= 4 sets of 13 genes
invertebrates = 1 set of 13 genes
Which phyla have radial symmetry? (2)
- Ctenophora 2.Cnideria
which part of the gastrula becomes the alimentary canal (the lining of the digestive tract)?
- the endoderm of the archenteron