The document provides an overview of the class Asteroidea (starfish). It discusses their classification in the animal kingdom, general characteristics, skeleton, symmetry, mode of life in marine environments, and methods of reproduction, respiration, feeding, and evolution. Starfish generally have five arms radiating from a central disc, come in various colors, prey on mollusks, and can regenerate lost arms. Their skeleton is made of calcium carbonate ossicles and they have a water vascular system used for movement and respiration.
Introduction
Ostracoderms (shell-skinned) are of several groups of extinct, primitive, jawless fishes that were covered in an armour of bony plates.
They appeared in the Cambrian, about 510 million years ago, and became extinct towards the end of the Devonian, about 377 million years ago. They were quite abundant during the upper Silurian and Devonian periods. Most of fossils of Ostracodermi were preserved in the bottom sediments of freshwater streams.
However, the opinion is sharply divided as to whether their habitat was freshwater or marine.
The first fossil fishes that were discovered were ostracoderms.
The Swiss anatomist Louis Agassiz received some fossils of bony armored fish from Scotland in the 1830s.
The ostracoderms resembled the present day cyclostomes (lampreys and hagfishes) in many respects and together with them constitute a special group of jawless vertebrates, the Agnatha.
Characteristics: They use gills exclusively for respiration but not for feeding . Earlier chordates with gills used them for both respiration and feeding. Ostracoderms had separate pharyngeal gill pouches along the side of the head, which were permanently open with no protective operculum. mostly small to medium-sized fishes, protected by a heavy, bony dermal (derived from skin) armor. bottom-dwellers; filter-feeders or grazers. no paired fins, but many with stabilizing paired flaps on either side of head.
(1) Ostracoderms were the first vertebrates.
(2) They were popularly called armoured fishes.
(4) They lived in freshwater.
(5) They were bottom dwellers.
(6) Their body was fish-like and did not exceed 30 cm in size.
(7) Paired fins were absent.
(8) Median and caudal fins were present.
(9) The caudal fin was of heterocercal type.
(10) The head and thorax were covered by heavy armour of bones. It protected ostracoderms from the giant scorpion like arthropods, eurypterids.
(11) Bony skull was well developed.
(12) Mouth was mostly present on the ventral side.
(13) They were having large number of gill slits.
(14) The nervous system had 10 pairs of cranial nerves.
(15) The head had a pair of lateral eyes, and a median pineal eye.
(16) They were filter feeders, feeding like a vacuum cleaner.
(17) The endoskeleton was either bony or cartilaginous.
Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres. Fish usually migrate to feed or to reproduce, but in other cases the reasons are unclear.
Migrations involve the fish moving from one part of a water body to another on a regular basis. Some particular types of migration are anadromous, in which adult fish live in the sea and migrate into fresh water to spawn, and catadromous, in which adult fish live in fresh water and migrate into salt water to spawn.
Marine forage fish often make large migrations between their spawning, feeding and nursery grounds. Movements are associated with ocean currents and with the availability of food in different areas at different times of year. The migratory movements may partly be linked to the fact that the fish cannot identify their own offspring and moving in this way prevents cannibalism. Some species have been described by the United Nations Convention on the Law of the Sea as highly migratory species. These are large pelagic fish that move in and out of the exclusive economic zones of different nations, and these are covered differently in the treaty from other fish.
Salmon and striped bass are well-known anadromous fish, and freshwater eels are catadromous fish that make large migrations. The bull shark is a euryhaline species that moves at will from fresh to salt water, and many marine fish make a diel vertical migration, rising to the surface to feed at night and sinking to lower layers of the ocean by day. Some fish such as tuna move to the north and south at different times of year following temperature gradients. The patterns of migration are of great interest to the fishing industry. Movements of fish in fresh water also occur; often the fish swim upriver to spawn, and these traditional movements are increasingly being disrupted by the building of dams.
Introduction
Ostracoderms (shell-skinned) are of several groups of extinct, primitive, jawless fishes that were covered in an armour of bony plates.
They appeared in the Cambrian, about 510 million years ago, and became extinct towards the end of the Devonian, about 377 million years ago. They were quite abundant during the upper Silurian and Devonian periods. Most of fossils of Ostracodermi were preserved in the bottom sediments of freshwater streams.
However, the opinion is sharply divided as to whether their habitat was freshwater or marine.
The first fossil fishes that were discovered were ostracoderms.
The Swiss anatomist Louis Agassiz received some fossils of bony armored fish from Scotland in the 1830s.
The ostracoderms resembled the present day cyclostomes (lampreys and hagfishes) in many respects and together with them constitute a special group of jawless vertebrates, the Agnatha.
Characteristics: They use gills exclusively for respiration but not for feeding . Earlier chordates with gills used them for both respiration and feeding. Ostracoderms had separate pharyngeal gill pouches along the side of the head, which were permanently open with no protective operculum. mostly small to medium-sized fishes, protected by a heavy, bony dermal (derived from skin) armor. bottom-dwellers; filter-feeders or grazers. no paired fins, but many with stabilizing paired flaps on either side of head.
(1) Ostracoderms were the first vertebrates.
(2) They were popularly called armoured fishes.
(4) They lived in freshwater.
(5) They were bottom dwellers.
(6) Their body was fish-like and did not exceed 30 cm in size.
(7) Paired fins were absent.
(8) Median and caudal fins were present.
(9) The caudal fin was of heterocercal type.
(10) The head and thorax were covered by heavy armour of bones. It protected ostracoderms from the giant scorpion like arthropods, eurypterids.
(11) Bony skull was well developed.
(12) Mouth was mostly present on the ventral side.
(13) They were having large number of gill slits.
(14) The nervous system had 10 pairs of cranial nerves.
(15) The head had a pair of lateral eyes, and a median pineal eye.
(16) They were filter feeders, feeding like a vacuum cleaner.
(17) The endoskeleton was either bony or cartilaginous.
Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres. Fish usually migrate to feed or to reproduce, but in other cases the reasons are unclear.
Migrations involve the fish moving from one part of a water body to another on a regular basis. Some particular types of migration are anadromous, in which adult fish live in the sea and migrate into fresh water to spawn, and catadromous, in which adult fish live in fresh water and migrate into salt water to spawn.
Marine forage fish often make large migrations between their spawning, feeding and nursery grounds. Movements are associated with ocean currents and with the availability of food in different areas at different times of year. The migratory movements may partly be linked to the fact that the fish cannot identify their own offspring and moving in this way prevents cannibalism. Some species have been described by the United Nations Convention on the Law of the Sea as highly migratory species. These are large pelagic fish that move in and out of the exclusive economic zones of different nations, and these are covered differently in the treaty from other fish.
Salmon and striped bass are well-known anadromous fish, and freshwater eels are catadromous fish that make large migrations. The bull shark is a euryhaline species that moves at will from fresh to salt water, and many marine fish make a diel vertical migration, rising to the surface to feed at night and sinking to lower layers of the ocean by day. Some fish such as tuna move to the north and south at different times of year following temperature gradients. The patterns of migration are of great interest to the fishing industry. Movements of fish in fresh water also occur; often the fish swim upriver to spawn, and these traditional movements are increasingly being disrupted by the building of dams.
Fins are the most distinctive morphological features of fish and they plays a predominant role for locomotion of fish under the water. It is important to know how many kinds of fins are present and their precise functions.
this ppt gives more clear information about origin of chordata. chordates are those organism which retain notochord in their life history atleast once.
looking after the eggs or young until they are independent to defend from predators is known as parental care.
Amphibians show great diversity in Parental care.
Fins are the most distinctive morphological features of fish and they plays a predominant role for locomotion of fish under the water. It is important to know how many kinds of fins are present and their precise functions.
this ppt gives more clear information about origin of chordata. chordates are those organism which retain notochord in their life history atleast once.
looking after the eggs or young until they are independent to defend from predators is known as parental care.
Amphibians show great diversity in Parental care.
Echinoderms - Asteroidea: phylogeny, anatomy, physiology and ecologyAdriene Oliveira
Classroom presentation about a group of echinoderms called Asteroidea (starfish). There's additional material in a pdf file called "Slide notes Echinoderms - Asteroidea". There you'll find the links to the videos mentioned in the presentation.
Echinodermata merupakan salah satu filum binatang invertebrata. Anggota filum ini adalah bulu babi, lilia laut, teripang laut dan masih ada yang lainnya.
There are main 5 classes of living echinoderms:
crinoids (sea lilies and feather stars); asteroids (STARFISH); ophiuroids (brittle stars); echinoids (SEA URCHINS, etc); and holothuroids (sea cucumbers).
Echinoderms have been well preserved as FOSSILS; all existing classes and several others now extinct were present in the Ordovician (505-438 million years ago). They may have originated in the Precambrian (over 570 million years ago).
Common name : sea lilies, Sea Stars(STARFISH), sea urchins, sea cucumbers, and brittle stars.
Habitat
Echinoderms occupy all habitats including coral reefs, mangroves, seagrass and soft-bottom areas.
Except for a few species which inhabit brackish waters, all echinoderms are benthic organisms found in marine environments. Echinoderms inhabit depths ranging from shallow waters at tide lines to the deep sea.(Barnes, 1987; Brusca and Brusca, 2003; University of Alabama Center for Communication and Educational Technology, 2000; Waggoner, 1999)
Habitat Regions
• temperate
• tropical
• polar
• saltwater or marine
Aquatic Biomes
• brackish water
Other Habitat Features
• intertidal or littoral
GeoGraphy and eco-system
Geographic Range
Mainly a marine group, echinoderms are found in all the oceans. (Brusca and Brusca, 2003)
BIOGEOGRAPHIC REGIONS
• arctic ocean
• indian ocean
• atlantic ocean
• pacific ocean
• mediterranean sea
Eco-system
Sea urchins are among the main herbivores on reefs and there is usually a fine balance between the urchins and the kelp and other algae on which they graze. A diminution of the numbers of predators (otters, lobsters and fish) can result in an increase in urchin numbers causing overgrazing of kelp forests with the result that an alga-denuded "urchin barren" forms.
Work cited:
Lawrence, J. M. (1975). "On the relationships between marine plants and sea urchins". Oceanographic Marine Biological Annual Review 13: 213–286.
Ecosystem Roles
Echinoderms are usually intricate parts of their ecosystems. Many asteroids are keystone species. Sea urchins, if not controlled by predators, may overgraze their habitat. Asteroids have several commensals, including polychaetes that feed on leftovers from the sea star's prey items. (Barnes, 1987; Brusca and Brusca, 2003)
Ecosystem Impact: keystone species
An impactful approach to the Seven Deadly Sins you and your Brand should avoid on Social Media! From a humoristic approach to a modern-life analogy for Social Media and including everything in between, this deck is a compelling resource that will provide you with more than a few take-aways for your Brand!
How People Really Hold and Touch (their Phones)Steven Hoober
For the newest version of this presentation, always go to: 4ourth.com/tppt
For the latest video version, see: 4ourth.com/tvid
Presented at ConveyUX in Seattle, 7 Feb 2014
For the newest version of this presentation, always go to: 4ourth.com/tppt
For the latest video version, see: 4ourth.com/tvid
We are finally starting to think about how touchscreen devices really work, and design proper sized targets, think about touch as different from mouse selection, and to create common gesture libraries.
But despite this we still forget the user. Fingers and thumbs take up space, and cover the screen. Corners of screens have different accuracy than the center. It's time to re-evaluate what we think we know.
Steven reviews his ongoing research into how people actually interact with mobile devices, presents some new ideas on how we can design to avoid errors and take advantage of this new knowledge, and leaves you with 10 (relatively) simple steps to improve your touchscreen designs tomorrow.
You are dumb at the internet. You don't know what will go viral. We don't either. But we are slighter less dumber. So here's a bunch of stuff we learned that will help you be less dumb too.
What 33 Successful Entrepreneurs Learned From FailureReferralCandy
Entrepreneurs encounter failure often. Successful entrepreneurs overcome failure and emerge wiser. We've taken 33 lessons about failure from Brian Honigman's article "33 Entrepreneurs Share Their Biggest Lessons Learned from Failure", illustrated them with statistics and a little story about entrepreneurship... in space!
SEO has changed a lot over the last two decades. We all know about Google Panda & Penguin, but did you know there was a time when search engine results were returned by humans? Crazy right? We take a trip down memory lane to chart some of the biggest events in SEO that have helped shape the industry today.
Inside this guide, you'll learn an insiders tips and techniques to getting into the marketing industry - no job applications necessary.
You'll learn what marketing really is, why you'll find a job easily, what entry level marketing jobs look like and four actionable things you can try right now to help get you into the marketing industry.
Visit Inbound.org and the Inbound.org/jobs community jobs board to find opportunities and connect with professional marketers from all over.
Phylum Mollusca-my report..
sorry for some overlapping of texts... i was not able to edit it..it is actually because of the animations that i put it..... i just uploaded it directly :)
This presentation was made for my 3rd grade homeschool son. It is divided into invertebrates and vertebrates. It discusses basic characteristics, life cycle, and types of animals.
Whittaker’s 5 kingdom classification
KINGDOM –MONERA
KINGDOM- PROTISTA
KINGDOM –FUNGI
KINGDOM –PLANTAE
KINGDOM -ANIMALIA
Microscopic
Unicellular(single celled)
Prokaryotes(without well defined nucleus)
May live in colonies or solitary.
Some of them are free living ,few are parasites
Some of them are useful and some of them are harmful disease causing
Do not have locomotary organs .
Few bacteria have flagella.
Reproduces asexually by binary fission (splitting into two)
Eg-Useful bacteria –Lactobacillus,Rhizobium
Harmful bacteria-Salmonella
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
4. General characteristics of Astoidea
• Usually sedentary along shorelines
• Starfish or sea stars
• Come in a variety of colors
• Prey on bivalve mollusks such as
clams & oysters
• Have 5 arms that can be
regenerated
• Arms project from the central disk
• Mouth on oral surface (underside)
10/19/2016 4
5. EXAMPLE (STAR FISH )
• Starfish or sea stars are star-
shaped echinoderms belonging to
the class Asteroidea. Common usage
frequently finds these names being
also applied to ophiuroids, which are
correctly referred to as brittle stars or
"basket stars". About 1,500 species of
starfish occur on the seabed in all the
world's oceans, from the tropics to
frigid polar waters. They are found
from the intertidal zone down to
abyssal depths, 6,000 m (20,000 ft)
below the surface.
•
10/19/2016 5
6. TYPES OF STAR FISH
10/19/2016 6
• Most starfish have five arms that
radiate from a central disc, but the
number varies with the group.
• Luidia ciliaris has seven arms, members
of the Solasteridae have ten to fifteen
while the
Antarctic Labidiasternnulatus can have
up to fifty. It is not unusual in species
that typically have five arms for some
individuals to possess six or more
through abnormal development.
•
8. Water vascular system
• Water vascular system: hydraulic
system for locomotion, food &
waste transportation, & respiration.
• • Water vascular system: consists
of set of waterfilled canals
branching from ring canal ( encircles
gut). The canals lead to tube feet,
(sucker-like appendages).
Madreporite is entrance of this
system
10/19/2016 8
9. Skeleton (body wall) & grade of organization
• Skeleton- below dermis
• made of ossicles (CaCO3)
• lattice like connections
• Calcium carbonate
• with spines and tubercles
• Muscle layer- below dermis
• Peritoneum that lines coelom
10/19/2016 9
• Epidermis- outer surface; includes
• mucous cells
• epithelium
• Pedicellariae- jawlike appendages of the
epidermis
• can open and close
• used to clean body of debris or put
debris on body
• Dermis- includes
• nerve cells
• connective tissue
11. Mode of life & Environment
• Mode Of life • Environment
Marine water
10/19/2016 11
12. Reproduction
• Most species of starfish are gonochorous, there being
separate male and female individuals
• Some species are simultaneous hermaphrodites,
producing eggs and sperm at the same time and in a
few of these
• Each starfish arm contains two gonads that
release gametes through openings called gonoducts,
located on the central disc between the arms.
• Fertilization is generally external but in a few species,
internal fertilization takes place
10/19/2016 12
13. Reproduction summary
• dioecious; external fertilization
• usually 10 gonads; 2 in each arm
• have fissiparity- division of central disc
into two animals
• free living larvae
• bipinnaria- first larval form develops into
• brachiolaria - shows development of arms
10/19/2016 13
14. Respiration
• Starfish rely on osmosis, in order to gather oxygen from the surrounding water The
hole on the top of their bodies is called madreporite.
• Water is gathered through the madreporite and fills a cavity in the center of the
starfish's body called the coelom.
• The coelom is intersected by a number of body canals that run from the center of the
starfish to the tips of each arm.
• These canals fill with the water from the coelom.
• The tube feet that are connected to these canals also fill with water.
• Carbon dioxide then flows through the thin skin of the starfish's tube feet and body
into the surrounding water while oxygen travels through the skin membrane and into
the starfish's body.
10/19/2016 14
15. Feeding and its mechanism
• Tube feet attach to bivalve mollusk
shells & create suction to pull
valves apart slightly
• Starfish everts (turns inside out) its
stomach through its mouth &
inserts it into prey
• Stomach secretes enzymes to
partially digest bivalve then
stomach withdrawn & digestion
completed inside starfish
• Starfish are powerful hunters and
primarily feed on mollusks. Their
main sources of food are clams,
oysters sand dollars and mussels
10/19/2016 15
16. Evolutionary history
• Echinoderms first appeared in the fossil record in the
Cambrian
• The first known asterozoans were the Somasteroidea,
which exhibit characteristics of both groups
• Starfish are infrequently found as fossils, possibly
because their hard skeletal components separate as
the animal decays
• However, although starfish fossils are uncommon,
there are a few places where accumulations of
complete skeletal structures occur, fossilized in place
in Lagerstätten — so-called "starfish beds
10/19/2016 16
18. References
• Lawrence, J. M., ed. (2013). Starfish: Biology and Ecology of the
Asteroidea. Johns Hopkins University Press. .
• Ruppert, Edward E.; Fox, Richard, S.; Barnes, Robert D. (2004). Invertebrate
Zoology, 7th edition. Cengage Learning.
• Byrne, M.; O'Hara, T. D.; Lawrence, J. M. "Asterias amurensis". Starfish:
Biology and Ecology of the Asteroidea. pp. 177–179. in Lawrence (2013)
10/19/2016 18
